I reached out to the game's author today and got an answer within an hour. Wow!
In case anyone had similar questions, the answers are below in bold, blue.
Assume for the questions that Robot A successfully grapples Robot B and Robot B is therefore held. Activation then passes to Robot B who fails to break the grapple.
Questions:-When Robot A activates again, are its arms already "in use", maintaining the grapple hold without a roll?-
-Can Robot A activate its arms and attempt a further Grapple, receiving a +1 since Robot B is currently held (the objective here would be to try to triple the defender's roll for the awesome throw)?
yes but of course there is the risk that the hold will fail and the enemy will break free
-Can Robot A activate its arms and attempt a different attack (like punch or slash), receiving a +1 since Robot B is currently held?
No unless it has another set of arms. Using the arms for anything else than holding would automatically set the opponent free and the +1 would not apply