w.r.t. points 2 and 3 . I am not in game theory, if I understood the problem somehow (?) I would just place the tangle into a potential V like a half-cylinder , its axis nearly parallel to the arrows. transaction in the lower parts of V get a weight (number>0) higher than transactions in the upper parts of V (near the 'shore'). every x-minutes there is a pulse in the tangle and all weights along each valid path contribute to S=sum of weights, a second number in each transaction. The path has opposite direction than each arrow. Where the path ends, the S there are priorities in order to put new transactions there. The tangle will grow faster, where the priorities are higher. If there are parts in the tangle, that have not changed for y-times, the pulse can start from there using the S in the new starting-points. Transactions in the upper parts of V should be confirmed with velocity 0.1 compared to the velocity in the lower parts of V, just think of a v_e_r_y long bath-tub, if You want to see V.