Good advice above. My 2 cents...
re: taste... Smoking wreaks havoc on your senses of taste and smell. Quitting temporarily wreaks more havoc, but it WILL improve in time. Also, your expectations versus the realities of what vaping can provide flavor-wise might be out of proportion at this moment, as were mine when I first started. There's a learning curve and experimentation involved in discovering what flavors really work for you day in and day out. What I thought was great when I first started (mainly high nic 'red type' liquids) now tastes horrible to me. If you'd told me I'd be vaping custard and tiramisu and loving it I'd have branded you crazy. And those favorites are temporary. Next week it'll be something else (that I never dreamed I'd like). Do a lot of switching between liquids. Strawberies are delicious, but if you eat them for breakfast, lunch and dinner you'll come to hate them quickly. Variety is the spice of life. Try it all, keep an open mind, and don't get bummed out when you burn out on a flavor. There's always something else you'll like more.
re, equipment...keep it simple, man! Kanger EVOD glass and EGO-C twists are my recommendation. Though I've since acquired a mountain of more exotic, expensive vaping junk, I never leave home without my venerable EGO-C EVOD glass. Compact, light, durable, and most important, eminently reliable. Just whip it out and vape it.
Vape stores are in business to make a profit, and right now it seems they're making healthy profits on Nautilus hype. With apologies to the hordes of Nautilus fans, mine is the most unreliable piece of gear I own. Actually, everything "Aspire" that I own has let me down at a critical moment. I love my MVP 2, and it's solid and reliable, but it's also a brick, so it stays at home. I also love to tinker with my Kayfuns etc....when I'm at home and within arm's reach of my equipment, but I would never consider taking them anywhere out of the house except to a vaping party. Go with EVOD/EGO-C twist (or something similarly simple) and work up from there.
re: relapse...I smoke-vaped for well over a month before I felt secure enough with vaping (mainly, my gear) to trust it completely. "What if this battery dies? What if the tank runs dry? What if it breaks? What if? What if? What if? I read between the lines of your post a good amount of the same 'distrust'. Don't panic! Allow yourself a transition period. If you feel you need a cigarette, smoke one. Smoke ONE...then back to vaping. Don't beat yourself up over it. Now's not the time to descend into self-defeat. Just keep plugging away and you WILL find your groove.
re: weight...It never ceases to amaze me how thoroughly my "Vanilla cake" eliquid has satisfied the (nightly) craving I used to have for twinkies (insert your preferred junk food here). Contrary to popular folklore, I've actually LOST 40 lbs. since I quit smoking. Keep it in mind.
Chin up, keep vaping, give it a chance!