1) How much of your time does it take up daily + Weekly?
No more time than looking after any birds, keep loft clean, feed water etc. A lot of time can be taken traveling to shows.
2) What would be good breeds to start SHOWING?
Pick an easy breed to start with but firstly decide on a flying breed like racer/show racers, tumblers etc or a fancy breed.
If you go for a fancy breed, find a show to go to and have a look at the diferent breeds, talk to the breeders before making a dessicion.
3) How much space do the pigeons require and how would you give them this (sheds, rabbit hutche, ect)
As with any, what ever size shed you have don't overcrowd it. Its much easier to keep birds clean than to have to clean them every time you want to show them.
4) How would you start up if you were going to start from scratch with mimimal costs??
Get a shed/loft, decide on what birds you want and then ask around and see what becomes available.