New South Wales
Here's some rule/FAQ quotes to back up why the answers are as Craig stated:
1: May I move to a remote system and than do nothing?
FAQ Errata section wrote:
The first line of the Rebel “Sabotage” mission should read:
“Attempt in any populous system.”
2: May I move (thanks to RM) the Unreveled rebel Base in a system with imperial units/loyalty?
RRG - Rebel Base - Establishing a New Base wrote:
The Rebel player cannot establish a base in a system that has
Imperial loyalty, Imperial units, or a destroyed system marker.
3: I mean, is there a blocking timing in the same combat round?
RRG - Combat - Block Damage step wrote:
• Damage markers assigned to a unit cannot be blocked.
Note that damage markers are assigned only after each blocking phase. This means the only things that can be blocked are dice and cards that have been assigned to units. If the second player were to try to play a blocking card they just gained from a die, they would actually only be able to block their own attacking cards and dice. The damage assigned to their own units was already converted to markers in the first half of the combat round.