Just a few basic ?'s

Hi Kotton, welcome to the boards! I'll try to respond to your questions in the order that they were asked.

Your proposed fish load is a little problematic. Due to the sizes and territorial needs of the fish, I wouldn't keep these four in anything outside of 180g, which is a little bigger than you had initially planned. Regarding intercompatibility, the trigger could potentially rough up the lion - I usually don't recommend mixing those two. One final thing to note is that either the trigger or the angel will eliminate your ability to keep corals - both are avid grazers of sessile organisms.

Your DSB (deep sand bed) is a good way to go as this will help with anaerobic filtration. A skimmer is also highly recommended. As for the wet/dry, it depends on whether or not you opt to include live rock in the tank. With sufficient LR, the w/d filter will be redundant. Without the rock, a w/d is your next-best option.

Special lighting is only necessary for keeping photosynthetic organisms, which won't be possible with the fish that you've chose thus far. (See above). Without corals, you can just use a regular fluorescent strip light.

No particular brand of marine salt is better than the others IMO. Shop around for the best deal and buy in bulk. You can typically buy buckets of salt that mix to 150-200g of saltwater.

You definitely need to invest in marine test kits. Freshwater kits typically will NOT work in saltwater, so buy new. You will at least need kits for pH, ammonia, nitrite, & nitrate. I would strongly suggest purchasing an alkalinity kit as well. You will also need to buy a hydrometer, a fairly cheap device for measuring salinity via specific gravity. Dechlorination is still required, although regular dechlorinator is fine in SW. (Just avoid dechlorinators with other "stuff" mixed in - no Stress Coat or any crap like that!)

Cycling typically takes a solid 3-4 weeks. During this period, read as much as you can get your hands on!

Post back with any add'l questions that come to mind!