I've gigged my amp with and without the mods listed. Mod 1, added filter caps will not be noticeable at lowish volume levels, but at gig levels, say master on 7, this mod tightens the low notes, makes them a little cleaner whereas they can be a little blurry and wooly without the mod. Recommended. Incidentally, its important to get the 350v or some other small version, room is tight to fit them. I had some 500v sprague caps, which are really too big to fit, I had to shoe-horn them by sitting them on the bottom of the PT - not great.
Re mod 5, it works in tandem with mods 3 and 4 at fattening the OD channel. Its very fiddly to fit the new caps, and I bottled it and fitted 100pf caps in parallel with the existing 270pf ones, giving me 370pf value. Sounds good though with the other mods done and suits me much better.
Re mod 2 - most of the vintage amp guys recommend changing Fenders from 470 ohms to 1K, so I'm not sure why there is a recommendation to change the other way. I cant see there being a noticeable sound difference and safety is increased at 1K, this is the only mod I havent done.
Al