Although I now have the very good Petzl Nao headtorch I still like to use a hand torch sometimes - the Led Lenser P5. It is sufficiently lightweight that it doesn't upset my gait and it is sufficient brightness a lot of the time. Also it is more handy to warn traffic when crossing junctions and the like.
First of all, I'd say you're doing your long runs at too similar a pace to your marathon pace. Secondly, for the race itself I'd try to be regular with intake. For example, I take on about 90 cal per half hour but this is a bit scant, since the body can probably absorb 250/hr. Broadly speaking, more might make you feel sick, as you are asking blood to be in two places at once: in the gut absorbing sugar, or in the muscles feeding muscles as fast as possible.
I just got the 220 because the strap mount on a 310XT has broken twice now. I like it a lot. Money no object I would have got a 920. Didn't get the 620 because I don't like touch screen and I have no need for automatic Connect upload via wi-fi (bluetooth with phone does the job.)
Autolap pop-up much more readable
Menus faster to use
Will do as a day watch, even with slim wrists
Battery display always there
Buttons easier with gloves
Lighter on the wrist
Much better charging clip
No breadcrumb trail to get you home in a strange place
No % heart rate max field
No level adjustment for backlight
Only max three fields per screen
Only up to 10 hrs in activity mode
Sound and vibration alerts/alarm a bit quiet
Has no power supply - uses USB
I don't think you can go wrong with it so long as these are not showstoppers.
Leg veins have little bags inside here and there as part of the system to stop blood pooling in the legs when standing. Gradually they stretch and possibly give you varicose veins over a life. Since we stand and move about so much it'd be very hard to make a case that the incremental change from foam rolling would do much to make that worse. In any case you're lying or sitting down, which already relieves the hydrostatic pressure. But it would definitely be more comfortable to roll to the heart if you're already tending in the varicose direction