You could write him a bit more detailed answers..
Twitch is better because the 25% block outshines nearly every other armor, especially when you play PvM (player vs monster).
With a 30/20 shield you can reach so called "max block" (75%). This is incredibly useful as you teleport around.
When compared to heavenly garb twitch also gives some hit recovery, what is useful for every char (read about hit recovery breakpoints below)/
For faster cast rate you should search for "fcr breakpoints" (faster cast breakpoints), they show you how much fcr items you need to put on your characters to allow them to actually cast spells faster
https://diablo2.diablowiki.net/Breakpointsin "classic" diablo (so without Lord of Expansion add on) most sorcs go for 70fcr, more is not needed
People write you about static sorcs, but no one told you that in hell difficulty monsters can have immunities (so for example: monster immune to cold cannot be killed with cold spells). This means that you will have to skip some parts of the game, since you simply cannot kill some monsters.
In fact some can be dual immune (say: cold + fire) although this happens rarely. Some people like orb+static, others like orb+firewall (+1 point in static). In my opinion most of those "two spell" sorcs kind of suck.
If you want to search for items (= "mf for items") best is to stick to one element, say frozen orb and just skip areas where you cannot kill. A frozen orb sorc can clear Andariel and Mephisto. She cannot do Diablo on her own.
Some monsters have cold resistance (similar to how players can have gear that increases their resistance). Your cold mastery removes it from them. As far as I remember you do not need more than level 17 cold mastery in Player vs Monster, since monsters do not have more resitance than that, so rest of points are wasted. In fact you could have say: 15 points, because a +2 skill amulet will give you 15+2 = 17
If you have a sorc without points into ice bolt and one without you would feel the difference.
Magefist is generally free starter item, but you can use spectral shard and 2 rings with faster cast rate, or amulet with faster cast rate to achieve 70 fcr. Easiest to do this with magefists obviously.