Good quality PVA to glue. Helps stop creaking.
Two of these makes it easier.
Nope, D4 (PU) is what manufacturers like Egger and Caberdecor actually specify (and is what they supply under their own name). The glue is applied to the tops of the joists and into the grooves. If you start with the groove side towards the wall (so the groove is left visible) boards can be pulled up quickly and efficiently by setting a 4 to 6ft length of 4 x 2in stud against the edge of a board, standing with your legs apart, toes on top of the piece of stud, heels on top of the chipboard, then giving a gentle tap or two (not smashing it) with a 7lb sledge hammer. Move the stud further along the chipboard and tap again as required to clise up the joints. This technique is far faster than using clamps and I dare say that a cheap skedge us a discarded piece of 4 x 2 will cost less to buy than you'd spend to hire cramps.
My personal feeling is that the PU glue is a bit more flexible (PVA joints aren't flexible and in any case PVA is designed for use on straight, planed joints, not sawn potentially slightly uneven joints as you get with joists) and the gap filling nature of PU helps deal with odd discrepancies and is less likely to creak in the future
OP the boards need to be screwed down one by one as you position them. That's ideally a job for an impact driver rather than a drill as ut will pull up the chopbosrd to the joist better (far faster, too). You will probably also need a couple of bars for the install (16in flat bar and a 24 to 36in wrecking bar) and some packing pieces (bits of stud) to bully small pieces into position and hold them whilst you screw them down (packers against the wall as a fulcrum, bar acting as a lever - the longer your bar the easier it can be)
If you aren't keen on using the sledge hammer technique, home made cramps are easy to make - you basically need to saw 3 or 4 pairs of folding wedges about 6 to 8in long (out of 3 x 2 or 4 x 2 stud). One wedge is screwed to the top of a joist 39 to 40mm off the edge of the board, using a single big screw (5 x 90, etc). The other wedge is inserted between the chipboard and the first wedge. Repeat until you have three or four wedge pairs along the edge of a board. Then tap the loose wedges to close up the gap between the boards. The bigger the hammer the better. Once that board has been fixed down, unscrew the joists and move them ready for the next board. Works with floorboards, too. As you can see I don't use flooring cramps. I never need them
