I'm gonna go backwards in trying to answer your questions:
Bolt-on vs. set-neck; neither one is better per se. Fender Strats and Teles have had bolt-on necks since their origins 5 decades ago. There must be something right about the bolt-on neck guitar because they sure do sell.
It's possible that the note sustain (length of time the note rings after being played) is a little shorter on a bolt-on but it's not a rule.
Set-neck guitars are great and an advantage to them is the ability to get a cleaner/smoother transition between neck and body which can help a lead player.
But there are great set neck guitars and great bolt-on neck guitars. And poor versions of both, too.
A hollowbody guitar (what Gibson calls an ES or electric spanish) is primarily an electric with somewhat of an acoustic body construction.
They can be lighter weight than the solidbody electric and have a slightly different tonal characteristic (less sustain, deeper sound) but for all intents-and-purposes, they're still an electric guitar.
Gibson ES-335, ES-175 and Ibanez Artcore series are examples.
A semi-acoustic or acoustic electric might be more of what you'd like. These are typically thin-body acoustic guitars that can be played unplugged (might sound a little thin and won't project far) but can be plugged into a PA an acoustic amp and sound very much like a traditional acoustic guitar due to an onboard mic and/or bridge transducer pickup.
They can be very lightweight and easy to lug around compared to a solidbody electric but they'll sound little like an electric guitar...as they should.
Gibson Chet Atkins, Godin A6, and Ibanez Talman are examples.
The most important aspect of an electric guitar is by fay the quality of wood used in the body and neck construction. This is what seperates the boys from the men, so to speak, when it comes to the sound of an electric guitar.
An electric guitar by it's nature and construction is still a very acoustic instrument.
When ever I check out electric guitars I ALWAYS play it unplugged to see how it rings and resonates. Many electrics, especially the cheaper ones, are totally dead when played unplugged and this deadness will transfer over when they get plugged in.
So I don't care if the guitar is made from mahogany, maple, poplar, alder, ash, basswood, cedar, etc...if it doesn't ring, it's not worth much to me.
Electronics like pickups, switches, wiring, pots and all that can be changed and upgraded but the wood can not. If the wood is dead, the guitar is more useful as a boat oar or stickball bat than an instrument.
You don't have to spend a lot of money to get really good quality. Ibanez and Godin make very good instruments for under $500. And there are good quality instruments out there for less but you've got to pick through a bunch of low-quality stuff to find it. Sometimes starting on a low-dollar guitar s not a bad thing as long as it's easy and comfortable to play.
Make sure the neck is straight, make sure the string action (height from string to fret) is low, make sure the sides of the fretboard/neck are finished and smooth, and make sure the neck/body joint is tight.
Hope this is helpful.