Basic How To Questions

[Jeff S]

I'm growing tomatoes in a greenhouse and have a few questions about basics.
1. I'm growing indeterminates and was wondering when and where to prune the lower branches as the plant grows.
2. The leaves are getting whitish stains on them. Is this from high humidity?
3. Is it better to grow new seedlings or just use the suckers from an existing plant?

This is probably the beginning of a bunch of other questions. Thanks in advance for any assistance.