2- There have been reports of acquisition of tanks and artillery by the rebels. Do we know if they have actually used them against government forces? Force-on-force battles favor the government of course given the balance of power but can we get a sense of what kind of strategy the rebels might use that would incorporate these heavy weapons?
Captured armor has been used locally and on a small scale, usually as fire support for attacks on checkpoints or bases. There have been only a few cases of tank-on-tank fighting. Generally the rebels lack the experience, ammunition, and maintenance support to use armor effectively. Tanks are also hard to use in what are often hit-and-run attacks.
More effective use has been made of indirect fire weapons, especially mortars, in attacks on regime installations. I think we’re likely to see greater and more effective use of heavy weapons over time, both as the rebels capture more equipment and as they gain practical experience.
There's plenty more at the link that you ought to read.