I got looking around and got thinking about trying/getting a beginner type RBA and I have a few questions
1. are these rba mainly for mech mods @ low ohms ?
No. though "it depends"
Are you looking to get into 'sport vaping' (blowing out HUGE plumes of vapour to impress your friends) or do you just want a decent quality vape?
You can run a Genesis style RBA quite happily on a VV/VW mod and punch the power up on a single coil at 1.5-1.8ohms and get good results. A well setup genesis will perform 'better' than a similar coil on a silica type of wick, you get a purer flavour, you get more vapour, you get more nicotine hit and more throat hit from a Genesis RBA. Basically the SS mesh wick (or SS rope or ceramic) can be heated to a higher temperature, allowing a hotter coil without effecting the flavour. Also silica wicks or ekowool, or cotton will add a small amount of 'wick background flavour' to your vape.
If you find you like the Genesis vape compared to your normal vape then you can get all low oms and mech mod, but you can start off and dip a toe in the water pretty cheaply for not all that much cash if you already have a VV/VW mod.
the best beginners Genesis RBA is the SmokTech RSST - have a look on the marketplace here. It's good because it has an insulated wick hole, a spring loaded centre post and the tank stops the wick from touching the base 'deck' all of which make it a lot easier to setup a decent working wick and coil in one than say an AGA-T.
2. can I get a tank and dripper type of rba in one ? (thinking dual type because starting to love mixing and something for testing instead of filling a tank)
yes an IGO-L is decent, as is a Smok Octcpus. Either of which can be fitted with a SS mesh wick rather than a silica wick.
3. does wicking with SS mesh truly give a better vape ?
Yes! - No! - how long is apiece of string? (twice the distance from the middle to one end)
That is subjective. for some people yes it's way better, for others it's not worth the hassle and increased juice use.
4. recommendations for a easy re-wicking/coiling most importantly & easy filling
For a tank setup the RSST is hard to beat and will set you back £25ish from a UK vendor. Whatever you do don't get a 'Chobra' (cheap cobra clone) For a dripper I'd go with an IGO-L though the Octopus is reasonable both of those are around a tenner, but they are designed for a silica wick.
If you want to try out a SS mesh wick you can actually put one into a lot of cheaper tanks out there already. There are YT vids all over the place showing you how to put one in a vivi nova etc