Saddle fit is a very personal thing, and it's a case of trial and error to find which one fits your backside. Many swear by Brooks saddles which mould to your shape.
I would carry on with the one you have until you work out specifically what you don't like about it, then search forums like this there will be masses of different opinions.
FWIW I have Selle Italia Flite trans am on my MTB, Fixed, And winter bikes. Specialized Toupe on summer bike. The Toupe is the most comfortable. I can very easily suffer from numbness and find the cut out helps me in that direction.
BEWARE SOFT SQUISHY SADDLES WILL NOT BE MORE COMFORTABLE (especially for longer distances)
As far as wheels go swapping will be easy (I assume you have 26" version not 700c?) Only issue is clearance for tyres. Personally, I'd probably save
money and just buy new tyres, swap them when needed.
Enjoy your new bike
