1. After a quick playthrough, level 16 Magnus has the following stats:

ST-11, CN-12, DX-14, BE-8, IN-11, WP-8, PE-8, CH-7; HP-74, FT-68; two ranks of Dodge and the Mechanical college, and three ranks in Melee and the Smithy college.

1a. You can have up to six followers, plus Dog: five for a CH of 20, one more for Persuasion expertise, and Dog is a free follower (he doesn't eat up a slot).

2. In a sense. The official player's guide gives a list of each character's build scheme, which should also be available to you through the game's modding tools; but it's difficult to calculate a given NPC's stats just from looking at them.

2a. I did some quick research of the game's NPCs I could find (ignoring one-shots like Doc Roberts and Thorvald). They're listed in order of their starting level when you find them; some of them I couldn't access offhand, because they were no longer available with my playthrough (I'll update this post as I find them again).

I also didn't list the end-of-game followers, because a) spoilers and b) by then you'll almost certainly already be level 50 anyway.

Virgil, Crash Site - Level 1
Sogg Mead Mugg, Shrouded Hills - Level 2
Jayna Styles, Dernholm - Level 6
Magnus, Tarant - Level 8
Gar, Tarant - Level 10
Dante, Black Root - Level 12
Dog, Ashbury - Level 12
Geoffrey Tarrelond-Ashe, Ashbury - Level 12
Vollinger, Dernholm - Level 15
Chukka, Tarant - Level 16
Jormund, Qintarra - Level 20
Torian Kel, Ancient Temple - Level 20
Waromon, Bedokaan Village - Level 20
Perriman Smythe, Tarant - Level 25
Z'An Al'urin, T'sen Ang - Level 29
Sebastian, Tarant - Level 30
Tollo Underhill, Dernholm - Level 30
Weldo Rubin, Gateway to the Wastes - Level 30
Raven, Qintarra - Level 32
Franklin Payne, Black Root - Level 35
Loghaire Thunderstone, Wheel Clan - Level 35