I recently started hardcoe and enjoy it thus far. Stimps healing over time seem actually heal more and the regeneration effect of it has other advantages. For my first few perks I've chosen Intense Training +1 Agility, Educated, Shotgun Surgeon and Cowboy. The Lever Shotgun is pretty satisfying so far. What I don't quite understand, is that some of soda beverages like Sunset Sas and Nuka increase the dehydration level. Is this attributed to the sugar content?

Any general tips and tips on decent perks in hardcoe?

Well not many tips but guess always have a fair stock up of water and food with a couple atomic cocktails on hand for sleep.

Also if use companions just don't run in to combat they will struggle with as once dead cant back plus don't hog loads of unneeded ammo as very easy for the weight to build up

With ammunition having weight it helps to have two weapons that use the same ammunition (357 magnum and cowboy repeater as an early example). The Survival skill is more useful, as a source of healing. You may want to boost your Medicine skill to 40 to make Doctor's Bags, or use other means of healing crippled limbs, like Weapon Binding Ritual or having the items to make Hydra.

Sounds like you are doing fine. One thing on the soda is it does add minor dehydration, but if you just keep couple Sars's for extra heals for fights your fine, I never drink enough to get in trouble with the meter. One thing I do that no one has mentioned, is if you find yourself travelling same route often, stash some ammo and food and drink long the way, saves you from running home and never bad idea to lighten your load a bit by making a new 'stash'