Neave seems pretty good but delivering her to combat is pretty unreliable and she doesn't do buffing, so if you can't get her in she feels a bit wasted. At least the Venator is always going to do damage until he dies. But, if you get her in, whoo boy she's a freaking blender.
I like Crossbows more than most people, but Bows are way way superior. Even with Crossbows you'll want your Prime to use the Shockbolt bow because it's just that good. Crossbows pair nicely with Scions of the Storm - just always keep them in Reserve and when they come in they'll be in range. But you often won't get to use the extra shots, so it's a bit iffy. Good against hordes, though, and that's becoming the meta.
Welcome, maybe! AoS is very fun and exciting right now, from my personal experience anyway. Lots of armies that are viable and lots of different missions and army archetypes. I never played Fantasy but I'm all in on AoS lately.
Goblins are quite good at the moment. Pure Gobbos won a big tournament recently, and pairing them with other Destruction armies is very powerful as well. I would tend to shy away from "legacy" models (that is, models that are no longer sold by GW and being phased out), but there are plenty of old sculpts that are still considered mainline and quite good.
As far as the gaps thing goes, the quality of the sculpts have, imo, gone up quite a bit and I rarely find any holes I need to plug. Depends on the model, of course.
But yeah, if you're interested, take a look through the rules. The base rules and rules for every model are free online, and I'm sure any GW or FLGS would be happy to have you come in and play a test game. If you have any questions, feel free to ask here as well.