1) i notice for ar 10 (plate), in arms law(at 20) entangling was easier due to the lack of maneuvering in plate as was MA sweeps,in CC it seems they did an about face and made it much harder to affect them
One of the things to keep in mind is that in Arms Law, armor types (AT) represent specific suits/sets of armor, while in Combat Companion the AR (armor rating) represent general materials/construction styles of armor.
Arms Law also used a very different paradigm in determining how damage was applied compared to Combat Companion. As I have elsewhere, you cannot just compare the two systems and expect them to match up. It won't happen - period.
There will be differences, and at this remove, I am not sure I can explain the thought processes behind them anymore (especially since my thought processes are heavily involved in another project).
2) when a player in plate is knocked prone how many rounds does it take for them to get back up?
Refer to Chapter 3 in RMC Arms Law (or the table on page 39 of RMFRP) for information on how long (i.e. what percentage of a round) it takes to stand up.
You could even turn it into a maneuver roll (using the Moving Maneuver Table) and having the result equal the percentage of the normal amount of activity required (i.e. if it takes 50% to stand from prone, and you get a result of 120 from the maneuver table, then it would take 60% activity (50 x 120% = 60) to stand up from prone.