There is no reason that you can't add a bit of sugar to increase ABV though it really shouldn't be necessary. @cmason1957
is correct though that you don't want to go to much since it will taste hot and the alcohol may overpower the wine. Make sure to measure your SG on Day 2 before adding the sugar and yeast starter since the concentrate is cold and might read a little low since it might not have dissolved all of the way to become homogeneous.
In regards to snapping the lid on after 48 hours, there is no reason that you can't leave the lid on loose and inspect as you have mentioned you do in your previous batches. That note in instructions is really to differentiate between the reds with skins and the whites. With the reds with skins, you have to get into your fermenter and punch down your cap twice daily. With the whites, it is not necessary.