mobile

Hey all,
So as it says in the title, I'm new to custom ROMs, kernels and all of that stuff. I've had my G3 since it came out, and with the G4 around the corner, I thought it couldn't hurt to start experimenting a bit with my G3 and see what more I can get out of it.
I've been on LGs stock ROMs since I got the phone, I've been too scared of bricking it or voiding the warranty to try flashing a custom ROM. But, digging around the dev section for the G3, I'm seeing all these custom ROMs and how well they're improving peoples performance, and I figured I might as well ask how to go out switching to one.
I had an old Google Nexus S (Yes, I know VERY old) that I had running stock with a custom kernel, but I only used that to toy around with. My G3 is my phone, it's my daily driver I use it for everything from my Music to communication, social networking, gaming, pretty much everything. But lately, a few factors have been driving me closer to wanting a different experience, namely:
- I seem to only have around 1.1GB of RAM free (I'm on the 3GB/32GB D855 Variant) after booting up, and after a few hours I get down to around 600MB free. This isn't ideal, and lag is a player after I open a few apps up. I'd like to get rid of the bloatware that comes with the phone that I can't force-close in the task manager.
- Battery life (Yes I know it's a QHD screen but still, I'm seeing people doubling their SOT with custom ROMs, and I'd like to be one of them!)
- General performance (The stock ROM is only so good)
- A few niggles I have with the stock ROM, just things I find personally annoying.

Now, basically what I want to know is the following:
- What's a good ROM to start off with and try on my device? I've heard good things about BlissPop v2.2, CloudyG3 2.2, ChupaChups ROM, and a few others but they're the main ones I'm interested in. I'd prefer a ROM that comes without all the bloatware on the phone, as I don't want to root to have to do this myself if possible.
- Do I have to root to do this? I'd MUCH prefer to not root my phone (even though I'm aware there's some good tweaks for the phone that lengthen battery life etc. but one step at a time, lets just start with a custom ROM) but I'm unaware if I need to root to install a custom kernel if it's needed for the phone (The Nexus S was given to me from a friend who'd already rooted it, I just wiped it and played around with it)
- How easy is it to keep the ROM/ROMs up to date? Is it like updating the stock ROM? Can I do it just by downloading the new version of the ROM and flashing it to the phone without having it wipe all my data (Like you do when updating the stock rom (From like V20A - V20B) Or do some ROMs have a built-in update feature?
- Is there any chance of me bricking my device and it being unrecoverable if I do this?
- Is there a guide to how to move from the Stock ROM to a Custom ROM somewhere here on the forums, or is it specific for each ROM? Mainly for the reason above, I want to avoid making my phone unusable so I want a good, solid guide if they're available.
- When I sell my phone in the future, am I able to restore the stock ROM and Kernel? Mainly worried about the kernel here, I know I can just factory reset and flash the stock ROM but not sure how I'd go about flashing the original kernel. If I could completely backup the original kernel and everything and then save that to my computer for later on, that would work well, I've saved backups of all my .kdz's for each ROM version.
- Is there a complete guide for backing up everything that is stock on the phone (ROM, Kernel, Userdata, etc.) and then starting over from scratch (Like a step-by-step process)
- *Optional* Does anyone know if I could restore my app data from the stock ROMs built-in backup tool in settings to the custom ROM if it supports it?

So that should be pretty much it, I'm really just looking to move to something more from my phone, and there's some good options out there, I'm just concerned regarding the things above. A huge thank you to anyone that's able to offer me help, you'll be doing me a HUGE favour. I don't think I'll be able to afford the G4 when it comes out I'm looking to get everything I can out of my G3.
Thanks! :D