No doesn't matter the order they are in, the "DIN" numbers reffered to are the easier ones to identify, but others include letters uk/italian plus numerous others.
Again doesn't matter at all whether it is 40 or 70, so long as at least 30 or so.
Get a relay holder for around a quid(pm me if you need, and I'll send you one FOC), then as you insert the terminals after CRIMPING the wires terminals together just make sure from looking at holder and underside of relay they go in the right slots.
You can apply a dab of solder onto the end of the wire AFTER it has been crimped, but just a touch, solder makes the wire brittle.
Just be aware for 70 amp relay that they will have larger 30 and 87 terminals, but again pm if stuck.
The std size of terminals is 4.8mm, larger are 8.8.
tabetha