A lot of lfs meeki won't even reach 6".
Lengths, between 3 and 5 " are more the norm.
You need decent stock to get them much over 6 inch.
The 7 " whoppers do pop up though so it needs to be accounted for.
if a salvini pics a fight with a meeki it will end up dead.firemouths are no match for them.
A pair of salvini on their own would be nice,or I would advise you loose the sal altogether.
Im not into telling people how to stock a tank butnif it were me i feel like withc sa/ca cichclids less is more. I would leave the severum off. You never know how they woll react to each other but i would probably either have the sev as the only cichlid or stick to the smaller ones.
Bioload may cause you to do multiple wc per week though. As for plants i say try it you wont know unless you do.
I have some cichlids that are known to eat plants but tried some annubias and they pretty much leave it alone