The rule is to put your pawns on the opposite colour of your bishop, in BOSCO's its particular true as they do not become targets for your opponents bishop.

mvh Fredrik 

In the second example, 3.Bg2 and 5.Bf3 make a very poor impression. Think you evalution that black is better is correct of course, but looking for how white could put up better resistance.  So the obvious move is 3f4 then something like 3...Kd6 3f5 Kc5 4pxp pxp 5.g4 Kd4 6.Bg2 This does not look too phleasant for white either, comparing activity of peices, and weak pawn on e4. At least white can try to create a outside passed pawn of his own, but doubt will be enough.

                I think it is sometimes possible to think of general strategies too much. (To be honest was scratching my head at what transpositions wrote). Better to just play the moves of position in front of us.

In the first example, from an evalution point of view white has worse pawn structure, and pawn down for nothing. Also black king is potentally more active. So black should be winning. Think also black does not need to rush, because white has  no counterplay, so black can aim to improve position slowly.Just remains to prove it in move by move analysis . Anway going with immediate 8...f4, which isn't really necessary, first obvious mistake is 12...Kxf4? instead why not 12...Bf3 then for example 13 Be8 kxf4 14Bd7 Bb7. At first, thought this was an easy win with g2ch followed by Kg3xh4, but black must watch out for stalemate defence with Bd5.  So 15Be6 then notice there is no stalemate because of a3-a4 whoops! so 15...g2ch 16Kg1 Kg3 is winnng after all.

 Bye John 

    In both examples you use Bosco's of the light(white) squares.  In this case the pawns that queen on the dark squares become very important, because the light square bishop does not control those squares.  In the second example you could use that advantge by combining the Knight and King to Blockade the diagonal that the bishop is using to stop the forward progress of the pawn to the queening square.

    In the second example, in general the plan for Black is to promote the advance of the outside passer pawn at b4, in order to prevent White from pressing forward with his 4 vs 3 pawns advantage on the kingside. 

   Black's Knight outpost at e5 (a dark square)  which cannot be attacked by White's light(white)square Bishop is a superior outpost to White's Knight outpost at e4 a (white square) which can be attacked by Black's light square Bishop.

  White's best counter plan is to exchange so that he wins the Minor Exchange.  Meaning White ends up with the Bishop and Black ends up with the Knight.  In that way White can press home his 4 vs. 3 pawn adantage on the kingside while simultaneously hindering the advance of Black's outside passer on b4.  Because the Bishop can move from one side of the board in one move and the Knight cannnot it out manouvers the Knight in positions where there are pawns on both sides of the board, and therefore battles on both sides of the board. 

Also important to note is that Black's outside passer at b4 queens on a light(white) square, the same color as White's lights square bishop.  This means that even if Black can manage to get his pawn to the queening square at b1, White can capture it with his bishop and still press home one of his pawns on the queenside while Black's King and Knight will be too far away to prevent it from queening.

Just to be clear Black definitely has the advnatage in the position shown in the second example.

These are just some ideas to help you along in your thinking about general strategies in these endgames.

I hope this helps.