Hi.
1. Comfort over everything else - if too hot take a pair of scissors to them and you will have North Face fleece running shorts ... though .. fleece? In June/July???? (keep what you cut off as you can nappy pin (diaper pin) them back together if you need to).
2. one jacket is best, can't wear both, take the light one - or a good poncho! Of which, fab thing to do is to put your waterproofs on, with your rucksack as the straps press into the material, and go and take a cool shower - you will quickly find out if they are waterproof or not. (anything waterproof that I buy I always re-spray waterproof it before using as I have found that factory waterproofing can be hit an miss).
3. Ah - should be lovely hot weather then but nowadays in western Europe the weather is a little odd - your decision but I would go for the liner only, if for some weird reason it does go cold you can always wear all you have at night!
But, really depends where you come from. I have known Aussies think it pleasantly cool when Scots were almost fainting in the heat - you know your body best!
Top tip! - Just remember that what you walk around with when 'testing' the weight at home is totally nothing like the reality of carrying that pack day after day after day - every refugio has an area where people just abandon things they no longer want to carry, so don't take what you want, take only what you
really need.
Buen Camino