Floorboard, glue or not?

[Lxxd]

I have decided to put engineered wood flooring, however the floorboards are creaking horribly.
Upon testing the floorboards and taking few out, I realised they need replacement, the wood is too dry, lifts at joist despite screws and creaks in tongue and groove sections as well.

So, I am about to order new floorboards and change everything. I have laid flooring before, but never floorboards. They come in variable length 2-5metres, and staggering them needs to be done carefully as the stubs are available equidistantly at every 45cm.

So I have two questions:

1. Should you stagger or lay the board at full length?

Obviously there would not be a groove to join boards vertically so if staggering, I would need to nail both ends of two adjecent boards, and joist stub is only 3cm wide, since boards are 2-5m it would be possible to stick then length wise across the room.

2. Should I use glue along with screws?

I found advice on using glue between tongue and groove, but I also saw advice on gluing to the joist.
Should you glue to the joist? This seams unsafe, and I will screw every board to joist either way.
Also which glue is suitable for tongue and groove, I have no more nail one for skirtings, but don’t know which one is suitable for flooring.

 

[motorbiking]

Are replacing the whole floor?

When you say the boards are too dry, what do you mean? Rot?

Why can't you lift the squeaky floor add a few noggins and screw back down?

I wouldn't glue - one day you will want to run something in the floor void.