O.K. You have against all better judgement decided to coat your own floor. Good for you. Who cares what the Shrinks think.
You will need at least two brushes and two rollers, three of each if you don't want to store one set for second coat.
One set for the Sealer and the 2nd set for the Two-Pack Polyurethane.
In their WET form the Sealer and The Polyurethane are NOT compatable. Meaning they don't play nice together when they are wet.
So don't stick a brush or roller that has had sealer on it, into your Polish bucket. It will help avoid a lot of problems.
If you are using a Two-Pack Polyurethane - Thinners Based such as Wattyl 7008, then you use the 55T Reducers. (Wattyls own thinners)
If you have a bucket with a sealed lid such as a big 20 litre pickle bucket, you can put 5 litres of thinners in it and then leave your brush and roller in that overnight or until you are ready to apply your second coat of Polyurethane.
If you let the brush or roller dry it will be stiff as a board.
Alternatively you can use three brushes and three rollers and just chuck each one away after use.
A 75 mm oval cutter is nice to cut in around the edgres, so you don't roll against your skirting boards or cupboards.
A 5mm or 6 mm Nap is best for Polyurethane. Don't use a shaggy dog 12mm nap like painters use. If you do your floor will be covered in an orange peel effect.
Keep dipping the roller frequently. Because you have such a fine roller, I can tell you to try and put heaps on the floor. But the fine roller won't allow you to put too much on.
Much better advice than the other way around. : )
Enjoy your insanity. Regards mark@qsand.com.au