That suit would work.... I'd go for the squat suit version as it will work better for squatting and about the same for deadlift, but at $100 more it might not be worth it to you.
As for the bands, you can get them from iron woody or EliteFTS and just choke them off on the top of any power rack.... You could get 3 or 4 different sets of bands ( different tensions) for 1/3 the cost of a suit and they will be more useful to you..... don't get me wrong, if you are set on getting in to a suit then go for it. I'd just hate to see someone spend $150 for something that they only want to use as a training tool when $50 of bands will do the trick.
As for briefs, they are worn under a squat suit and basically are just a suit without straps..... they just add even more support for the hips without restricting the torso. That and when I squat in a canvas suit, the suit stops me cold in the bottom but doesn't offer much rebound, so you pair that suit with a stretchier brief that gives carryover throughout the lift but has no stopping power.
Most guys train a lot in them ( or the single ply guys do similar work with just the suit bottoms) because in gear most guys squat using different form than raw.
My raw squat ( and I never max out on this) is well over 650... as in, I have hit 650 in training just for fun, didn't struggle and then just got my briefs on... I'm probably somewhere in the mid-700's.
But the raw squat is rarely worked in my training cycle because to squat raw you need a narrower stance so you can use more quad drive. My competition stance is wider than most power racks, about 2" away from the base of the monolift. If I tried this raw I'd rip my groin or just miss the weight badly.... so in training I do most of my squatting in briefs. This allows me to still do more work with lighter weights than I'd use in my suit, while still using my competition stance. In just the briefs I've gone over 900, then up to 1100 with reverse medium bands. My full squat in a suit has gone as high as 1060 in the gym, and just under 1000 in a full meet. Not tryng to brag, just giving you an idea of what sort of carryover every bit of gear provides and how we train in it.