You'll have to submit 6 months wage slips, six months bank statements, and your savings account statements. I think that you will probably have to write a letter of support for her application and include evidence that you have adequate accommodation for yourself and your wife. If the house your living in is not owned by you or rented directly by you, you will also need a letter from the owner or person who's name is on the rent book, saying that it's OK with them for your wife to stay there.
Why don't you apply for a spouse visa, if she gets one she can stay here or come and go for up to two years. If she comes here on a family visit visa, I'm not absolutely sure about this, but I think she might need to take out medical insurance to cover the period of her stay as well.
Iain.