If you're going for a tank build (stand there, violently attacking and taking tons of damage) go heavy. This would be melee > magic.
If you're going for a kiting build (run around, fire off spells, then run in and attack) go light armour OR (IMHO a better option from what I've seen; the stat boosts are huge) enchanted robes of something. This would be for a magic > melee build.
And if you're looking for bonuses, I believe they are equal. If not, just enchant your own.
If Tamara Wijsman's formula is correct, hp can be factored out of the formula. Also, there's a 12/100 factor I saw from uesp.
resulting damage = damage * (1 - armorfactor)
armorfactor = 0.12 * (hidden armor + displayed armor) / 100
hidden armor = 100
Which gives these values.
50 armor -> 18% reduction -> 82% damage taken
150 armor -> 30% reduction -> 70% damage taken
317 armor -> 50% reduction -> 50% damage taken
442 armor -> 65% reduction -> 35% damage taken
567 armor -> 80% reduction -> 20% damage taken
The hidden armor in the formula is when wearing four pieces of armor (chest, head, hand, legs). If you are wearing robes or hood, or are missing feet or hands, then hidden armor is less than 100 and you get less reduction. This reduction in reduction is not reflected in the displayed armor rating.
Finally, damage reduction is capped 80%, so 567 is the maximum displayed armor rating that is useful when wearing four pieces of armor. 667 is the maximum displayed armor rating that is useful when wearing 0 pieces of armor.
Best Answer
No.
Glass armor does not appear in leveled lists until you are level 36. Allegedly they can appear in boss chests or merchant inventories at around level 26.
You can find a pickaxe and mine malachite from the Glacial Cave or Nchardak, assuming you could survive there at level one. However you can't craft glass armor without the requisite perk, which requires 70 Smithing, which you can't really get without leveling up a few times.
There are very few fixed sources of glass armor; Northwatch Keep and the Thalmor Embassy have guaranteed Thalmor spawns, but they won't be wearing glass armor until you're level 36. They're in Skyrim anyhow, not Solsthiem. I don't think Solstheim has any fixed spawns of the armor or creatures that would wear the armor.
Your best bet for getting it as early as possible is probably to level only Smithing until you hit 70 (to keep your level as low as possible), taking the appropriate perks along the way, and then make a beeline for a malachite ore vein and craft the armor yourself.
Or to cheat.