Similarly a Bull Rush is an Attack (part of a Standard Action, but not necessarily the whole thing).
That's not my reading. The sentence is "You can make a bull rush as a standard action (an attack) or as part of a charge." First sentence of Bull Rush rules, PHB 3.5, p154 in my copy, or
http://www.d20srd.org/srd/combat/specialAttacks.htm#bullRush.
I take that to mean that a Bull Rush is either a standard action, a special variant on the Attack standard action, or (including moving up to twice your speed in a straight line etc.) it is a full-round action, a special variant on the Charge full-round action. Probably also, in a surprise round, Bull Rush incorporating moving up to your speed could be a standard action, a special variant on the standard-action charge. I do not see it saying that a Bull Rush can be just one attack in a Full Attack sequence. (I might be tempted to house rule that if you start adjacent to an opponent you can full-round Bull Rush them and get iterative strength checks to the same number as your iterative attacks, at the same penalties, and with a distance limit equal to twice your move, but I don't see that anywhere in RAW.)
I think it does work to start a grapple with your first attack of a Full Attack sequence and then with your next attack pin them for the rest of the round, including preventing them speaking, and potentially do certain other things with third or subsequent attacks, if you have them. But since speaking is a free action and can be done even when it isn't your turn, that doesn't stop the victim calling out between the initial grapple and the pin. Also, as I said before, moving the grapple is a standard action, not part of a full attack sequence or even a move action. You would have to do that in a subsequent round.
I don't see a way under RAW to silence someone with your first grab. Films and folklore about the special forces etc. suggest this ought to be possible
if you catch someone by surprise from behind, but I think it may also need a house rule. Maybe a special Grab stage with -4 on the melee touch attack (and if you want to do the classic stifle-and-stab combo, either the hand over the mouth or the weapon will need to be your off hand).
OP LordPhrofet has rejected in post #3 the option of using a surprise round and then winning initiative for the first full round, saying it provides too much opportunity for other characters to see what is going on. Presumably they might make their Spot or Listen rolls and not be surprised in the first round, or might get a better initiative result than the attacker, even if the victim doesn't.
The net-equivalent blanket is a nice idea. A strict DM might make a continuous cloth less effective at entangling than a net (I would - the thing about a net is you get limbs and kit caught in the holes, not just wrapped up in it), but OP is the DM so can choose not to.
I'd say pulling an entangled victim towards you, or after you as you move, is a legit use of the movement control function of the net. You couldn't push them away or move them sideways, unless maybe you had your net on a strong pole, and even then I'd assign a penalty to your Strength check.