Depends on what you like. For a race to learn the game with.I've heard that Man is quite newb friendly, Lanka and Hinnom are blood races so you need to get yourself started with blood hunting and stuff like that(I myself still don't know how to efficiently do that) They are definitely strong but you might get a bit confused with them. Ma Aghartha is something which you might like you get to summont loads of tough units. Nifelheim will be an easy start for you, you can just buy all the Sc you want.
But yea Giant races will do well against many computer opponents mainly because their PD is really tough
A trick you can do (its going to make your life easier untill you learn how to use most of the spells and communions and alike, is to put loads of PD 50-60-70 on chokepoints the computer will try attacking it and fail most of the time)But I only suggest you do that if you are pressed hard from 3-4 sides.Also Helheim is good for a bless strategy.Just buy loads of sacreds and buff them with your amazing dwarf mages: Iron warriors, Strength of Giants and later on Weapons of Sharpness, Army of lead, Army of Gold.
On good map question - random map thats what I always play on
Age - depends on whether you like strong fantastical units more or big and well equipthed armies. For fantastical units go Early age, for mix between the two Mid age, and for Strong armies(durable units and other nice stuff) -late age.
Hmm settings normal I guess, but that is just me I like everything to be even between me and the computer opponents.
On good pretender advise, get bless or SC-pretender it is easier than starting with rainbow pretender.