Regarding snails on plants... unfortunately i do have to recommend either a) undertaking dips to treat for snails if you get your plants from a shop tank there are a few methods such as the one fcmf uses. Regardless of the quality or source of the plants in question, more often than not, shop tanks have acquired snails over time (customers exchanging their spare plants/trimmings for store credit being one source), and/or b) being very careful with the plants you buy. I cannot recommend Tropica enough here. There are a few growers that do tissue culture plants. Tropica's are the easiest to prepare for planting. These pots are a bit more expensive but contain loads of little tiny plantets that have been grown in lab conditions in a nutrient rich liquid so guarenteed to be snail free. Tropica also do blister packed plants available in Pets at Home. These are not technically guarenteed to be snail free but the chances are very strong they will be. They are growing emergent (out of water) in the packs and therefore often more healthy plants that the ones the shops bring in in bulk. They are also not underwater any any point before they reach you so snails have no chance to lay eggs in anything other than the pot, seeing as you will be removing the pot... there is very little chance indeed of introducing snails.
Final note... if you go for tissue culture plants OR a lots of crypt species (regardless of type, as they commonly 'melt' as they adapt to growing in your tank) get some fast growing 'supporting plants' to see you through the first couple of months as these will suck up any excess nutrients and limit the algae common in new set ups.
Hope that helps! (I'm not sponsored by Tropica by the way... just a genuine recommendation here...)