I have a question, I have two small ones that I wo...

some photos would help a lot. LST is light stress training and great for shaping and managing plants. HST is HIGH stress training and is only recommended in veg for photoperiods, autos do not do to well with it. I'd say go LST.

I find that topping or filming is the best to do. Just make sure you have at least four nodes up to top. I have plants that are 7 weeks old. They're 20 in tall and 34 in wide. They've been topped eight times. Their yields are about triple what they normally are.

Mainlining (or sometimes called manifolding) is a more drastic form of training that involves multiple sessions of topping branches to build out an even and equal framework for your plant. It takes a lot longer than basic LST training because you have to give the plant time to grow some between toppings. If you're wanting to do something "quick" then stick with basic LST to break apex dominance.