I am badly stuck on a few Newton's Laws problems. I hope someone can help me out! Thanks a million!

1) A 5 kg block rests on a 30 degrees incline. The coefficient of static friction between the block and incline is 0.20. How large a horizontal force must push on the block if the block is to be on the verge of sliding

1a) up the incline?

1b) down the incline?

I really have no clue of solving this. Would 1a and 1b have the same answer?

2) A double incline plane has two boxes of equal masses on opposite sidesconnected by a rope over a pulley. The left incline is 53 degrees and the right incline is 30 degrees. The coefficient of static and dynamic friction are equal, 0.30 for both boxes.

2a) Show that the system, when released, remains at rest.

2b) If the system is given an initial speed of 0.90m/s to the left, how far will it move before coming to rest?

For 2a, I know that the motion of attempted of the system is to the left beucase the left incline is steeper and the boxes have equal masses. So there are 2 frictional forces, both pointing to the right. Knowing all these, I got that the acceleration is 0.69441m/s^2 [right]. Then, how can the system remain at rest? Can someone explain? I don't understand.

For 2b,v1=-0.90m/s,v2=0,a=0.69441. Using these, I found that the system moves 0.58m to the left before coming to rest. But can I use the acceleration that I got in part a? Is this the correct way of doing it?