Hi, some ramblings as my first post:
#1: While I agree that Captain Giggone doesn't search for new cadets just out of the goodness of her heart (the prestige alone is an ulterior motive; and it it mentioned at least once that she would feel more pressure to teach at the academy without that shtick), I don't think that she would actively torpedo the careers of her (ex-)crew members who choose another path.
I tend to agree - I don't think she would torpedo someone who didn't do what she wanted - but I can't say it would be completely out of character. There is a reason Kipling said "the female is more deadly than the male." I think she put the needs of the Merchant Marine service first, and didn't really consider very well what Ishmael's needs were, and whether he would be more effective with more seasoning.
#2: Generally speaking I think that Giggone isn't as awe inspiring, as she was for young Ish:
the whole "your ass is mine" speech for land rat quarter shares just doesn't sit well with me. Even more so since it is well established that the union halls screen non-spacers quite thoroughly. She had to know that both Ish and Sarah thought that the berth on the Lois was their last hope, and they were classified as "good people" by the union hall managers. No pressing need to "scare" them into submission/on the straight and narrow. Especially in Sarah's case it struck me as almost cruel, and far from good leadership.
To be fair, the "scare them straight" approach is classical, and probably pretty much mechanical for Capt. Giggone. And it's classical because it's very effective, working on a large majority of the population. It likely arises from our pack/troup evolutionary history. However, it's the ones it doesn't work on who are the most critical - they're either going to be your brightest stars, or your biggest headaches. I was the latter for a trio of Drill Sergeants during Basic Training at Ft. Benning for the National Guard.
And she seems to be rather aloof and cloistered in her cabin. A far cry from Captain Rossett to be sure, but not really all that involved with the crew. Granted, the Lois isn't a Fast Packet where the Captain cooks breakfast, but a crew of 33 isn't a terribly big crew either. At least by the standards of present-day navies.
I agree, but again, this is classic separation of the Enlisted and Officers that is held strongly still in our military. Truthfully, Ish didn't do so well on this, and I'm glad for him.
#3: I never understood the "you have time, but don't waste it; go to Port Newmar NOW!" scare (well, I kind of understand if out-of-character: the next book was "Double Share," so Ish had to be an officer by then). For starters we talk about a universe where people routinely live 140 years and people with careers work past 100.
And: all the other cadets from the Lois (Pip, Bev, Brill) were both older and had spend more time "seasoning" as ratings. That double standard always bothered me.
They also never went for the all four ratings thing. Pip actually had issues he had to resolve in himself before he was ready - though to be fair, his father rushing to meet him gave me the impression that Pip came by these issues fairly. However, Bev & Brill going for the Academy at that time was either mostly coincidence, or just something they got inspired to do seeing Pip & Ish heading out.
#4: I don't see Ish as a rating "for life." I think Sandy Belterson was right: enlisted
are "labor" and it
is a "dead end job."
And Ish is just too learning and career orientated, he had his "full set"
and his fist Spec/1 rating in the first two years. He could have worked to become Spec/1 in every
specialty 
, but I don't think that is a realistic option.
But: two years or so of insight into the more indie or family side of spacer life would've been very valuable for a land rat like Ish (and I think even Captain Giggone would've seen the wisdom of that).
Sandy may be right - but not everyone is really that interested in going on to a leadership position, even if they're otherwise qualified for it. Becoming Spec/1 in every specialty would have been well within his grasp, and might well have been something he really enjoyed. I'll agree that he was learning oriented - I'm not so sure he was career oriented.
I think, though, that for the most part, Ish integrated so well, that most people simply forgot that he wasn't spacer-born. This lead them to assume he knew a lot of things he didn't - such as Ish's constant discovery that things were available on his tablet, like the map of the ship. We don't generally use GPS for navigating our way through a building - we look for signs and a building directory posted somewhere prominently.
Just imagine Ish taking Penny's offer to find him a berth for his "very marketable skill set" and spending two additional years as a rating on board of a family run Fast Packet before going to Port Newmar.
A berth where his wide cross training is actually used, valued, and further encouraged.
Remember how Ish grows under von Ickles, a Third Mate with just three years under his belt? Imagine Ish after a Captain and a Chief take him directly under their wings for two years: not awe inspiring figures in the cabin, but people who hold a spatula or change scrubber cartridges too.
Not to mention that he would most likely experience an alternative to the "don't screw with crew vs bunk bunny culture" he so mightily struggles with.
Indeed - Ish would have developed rapidly as an apprentice on the Bad Penny. And I think ultimately, that style of ship command - a small crew of people he knows very well, and can trust fully - would be the best place for him, if he eventually did want to go into command.
Still, he got to where he is now, though at least three women had to die for it. We'll see where it goes from here.