Reliability is a function of the correct gear and correct installation.
Ham radio can be a great means of communication.. but... food for thought... I have a shitload of firearms and firearms related stuff.... I have more money in radio gear than I do in guns and shooting gear.
I doesn't have to be expensive, but it can sneak up on you.
You have to decide what "kind" of communications you are looking for and lay out a logical approach to reaching that goal.
Home setup can go from a HT sitting on your couch all the way to having multiple towers with azimuth AND elevation control on very large antenna arrays and more wire in the air than the local power company....
Your biggest issues with the mobile gear is going to be high temps for the RT and battery power to run it (as well as being able to start your car) if you're going to use the mobile as a cross band repeater.
One of the larger considerations is whether or not there are any VHF / UHF repeaters that cover the area you are going to be in.
Without a repeater, VHF /UHF is pretty limited for a handheld. Mostly LOS.
With a repeater? You can talk around the world through frequency agile crossband or INTERLINK / WIRES /VOIP connected repeaters using a hand held on your end- IF you can access the repeaters with that functionality.
What I tend to do is set my mobile RT up as a crossband repeater (VHF in UHF OUT or UHF in VHF out) so that my handheld talks to my truck, and then my truck turns around and talks to the actual repeater. BUT... while I'm using my handheld with a stubby antenna and 2w-5w to talk to my truck my truck then turns around and talks to the repeater on 10w with a 5.0 or 7.7 dbi gain antenna and when the repeater talks back to my truck the truck then talks back to my handheld with 10w with a high gain antenna.
Kinda like linking multiple retrans sections together and talking across NTC with an MBITR on 30-88mhz.
Now... doing this with my truck... I have a gel-cel battery that runs the RT as well as a roll up panel charger sitting on my dash to help the gel-cel keep up.
I've killed my truck battery too many times and have learned to use a separate battery for the RT.
You can always try to do QRP HF, but you'll get tired of lugging batteries and solar panels and trying to catch the propagation right for the band you're trying to use with whatever antenna you have.
Understand.. that unless you're talking to someone else with a ham license... you aren't talking to anyone. You CAN do VHF / UHF phone patches, but there are limits AND you have to remember ANYONE who can hear the repeater can hear your phone conversation - and if so inclined- disconnect you at will.
Now ... did I answer more of your questions than the questions I have created in your mind?