Very intelligent questions. I try to answer:
The Universe is all U.S. listed stocks, ADRs or LPs and MLPs.
The number is limited by my parameters, they are very strict. Sometimes I don’t get a single stock to buy in 3 months. But sometimes there are several the same day.
Replace: it is the other way around, when I buy something I sell the “worst”. I want to be invested always according to my leverage quote. If I have liquidity lying around I do “soften” my criteria, if I still don’t find anything for more than 5 market days I add to existing positions.
If I have 2 stocks but only liquidity for one I buy both and sell again the “worst” holding.
I already wrote about it, there is one main difference between the dividend and the momentum strategy. In the dividend strategy I always find enough companies to buy. I buy when I have to sell to maintain my quota. In the momentum strategy it is the other way around, I hardly find any stocks. If I find one I buy it. If there is no excess liquidity the “worst” holding is thrown out.
So the divi strategy is “pull” while the momentum strategy uses “push”. Both do not like cash.