Before you complain about us giving you bad advice, consider this. We have next to no information about you. We know your height, weight, budget, and how you plan to use the bike. That's it. We don't know what kind of trails you plan to ride. Trail exploration can mean so many things. Sometimes I explore trails on my 4" weenie bike, because I've been told there's a lot of climbing but nothing super tech-y. And sometimes I take my big ole' hardtail, because I know there's going to be some stuff to play on and I want a slack bike with cheap components where I'll care a lot less if I trash a derailleur. You're an ex-BMX guy, so my first instinct is to tell you to get a geared DJ that will handle jumps, stairs, and drops. But then you say you want an all-purpose bike for commuting and long trail rides, and a DJ will Suck with a capital S for that. So give us more information about how you want to ride this bike.

Sizing is all relative. One company's 17" is different from another company's 17" since every company seems to measure differently. Plus geometry makes a huge difference. Reach and stack are more important measures than seattube size due to differences in geometry (reach is horizontal distance from bottom bracket to headtube and stack is vertical distance between the same two points). Why? Because your butt's not always in the saddle. But you don't know what the best measurements are for you anyway, and unfortunately we can't figure it out online, since everyone's proportions are a little different. So you need to go to shops and try bikes out, then buy whichever one fits the best. The best bike on paper that doesn't fit you in real life is a bike that will sit and never get ridden.

Are you sure you can't adjust the fork? I didn't Google the bike, so I don't know what's on it, but with an air fork you can add or remove air, and with a coil fork you can put in a different weight spring. And if it's a cheap fork, there's not much you can do to fix it. Also, some people might come on here and say to get a fork with lockout, but lockout is overrated. A good fork won't bob and negates the need for lockout. A cheap fork's lockout doesn't work. So don't worry about lockout. A fork where you can adjust the rebound is a plus though, and your shop should be able to help you dial that in (you can fine tune it as you ride it).

Finally, this is your first bike, right? 99% chance you don't know what you want (so we definitely don't know). You might think you know, but as you ride and get experience, you'll realize your first guess was wrong, and you'll want something a little different. A bike's not something you buy once and have forever. It's something that you upgrade and replace as you get experience. Also, there's a good chance you'll trash your first bike. As you're learning to ride, you'll fall and trash its components. You'll trash stuff on later bikes too, how much depending on what direction you go with your riding, but no matter what, expect to abuse that first bike. Most likely, you won't always keep up with maintenance as well as you will with later bikes either. I trashed my first bike and I'm not the only one. So don't buy this bike expecting it to be the be-all-end-all.

Hope that helps some.