Getting under one hour here is a bit harder than Episodes I-III. The Original Trilogy has a lot longer levels. Case in point, Through the Jundland Wastes and Mos Eisley Spaceport. A New Hope is the shortest of the OT though, so around 40ish minutes shouldn't be a problem. Getting 100,000 studs is harder than LSWII. You don't get as many studs from objects as you did in LSWII. Secret Plans is still useful for Stud Collecting, but you'll likely only get 40,000. Rescue the Princess is also quite useful for studs while running down the hallways with a Power-Up, and Rebel Attack has pretty much everything you can destroy give studs, so that's a great stage for studs too.
Location: Mos Eisley
Time Limit: 5 Minutes
This one is not too bad but can give some trouble, Mos Eisley has narrow corridors abound. Blowing up metal objects gives more studs than other things, so try to get those as much as possible. 5 Minutes isn't long, but it is do-able. Run around, shoot, and destroy as much as possible, it all respawns eventually anyway, so make loops around the area. Power-ups make things nicer to deal with, but they aren't as plentiful here in my experience as in other stages. Never stay in one place and wait for everything to respawn, you'll fail if you do.
Location: Death Star
Time Limit: 5 Minutes
This one's easy, and is made even easier in TCS with the addition of the Power-Up! Pick a Vehicle, preferably one that flies, and shoot everything. Remember to pick it all up though, but you'll find yourself hitting the total very quickly. If a bit behind, use torpedos to hit the posts, they'll drop some good studs. Getting under a minute here is very easy to do.