Blooms throughout the year

[IB STRAMEZI]

Hi. I just built a 2'x4' orchid bench and hung a T-5 lighting system over it to supplement pretty dim natural light. I am new to orchids. How do I select plants now that will bloom at different times during the year? If I buy from a nursery, I'll just get varieties that bloom at this time, no?

Also, about how many plants can I expect to fit? I do have four oncidiums in a windowsill that I bought from a private party recently, and the leaves on those are quite large. Do phals and phaps grow to the same size?

Thanks.