Agree fully, straps are like shoes, or harnesses and so on - different personal likings and physical differences in feet too
You gotta find out yourself !
Sounds like a "what kind of advice is THAT ?" - but seriously, noone will ever be able to tell you what strap will work for you, unless you have an identical twin brother with the same preferences maybe
Apart from that:
They should not be too tight - especially not the front one, compared to a TT.
You must never ever have to "wriggle" your feet in the straps - then it is all wrong I would say.
The bump in the middle is for being able to twist your foot easily in the straps, and still being able to hold the board with your toes, when doing high jumps or aerials
Can also be used to feel where your feet are strapless as noted.
The Naish Gun is an awesome board, and quite amazing and not riding like a "big wave gun" at all, so enjoy your board
Some like wide straps like on twintips, other likes narrow windsurf style straps (I do myself - WAY better for me personally...)
The front strap should be a bit looser than the rear one IMO, and the rear should fit bullseye, in order to REALLY be radical and have a tight grip both when doing flat tailslides or steep power cutbacks.
Again, that is my preference only - some like straps really big.
The position is important - dont put the rear strap too aft if new to directionals.
And dont ride the rear strap at all when going upwind or in light wind - unless you are new and have moved the strap forward to fit for "starters".
You dont have to get your feet over the middle of the board
(well, your toes yes)
Strapless, yes, you have no other choice in order to put pressure on the board on the leeside rail.
But that is one of the advantages strapped - that you have more options and leverage, and can in fact have your feet slightly away from the center, and still put lots of pressure on the leeside rail
And the heelside rail can be loaded a lot too
This is especially important for wide boards and a huge advantage - where you strapless sometimes would have to move your foot from leeside to heelside in order to put pressure on the rails with "weight".
Again - it is two riding styles that can be VERY different (and also similar if you want) - I love both strapped and strapless because of this, but strapped gives you a lot of options IMO (others would say the opposite, I know, but lets not get into that discussion here...).
From an old thread two years ago, here are my preferred "windsurf" straps - I use the same on my newer boards today :
Just to show how different likings there are - others dont like above, some just loves these - so you have to find the right ones yourself.