1.) No reason not to take Spirit Weapons for Parry! Hunters will Misdirection you anyway, plus your spells on-pull will generate a good deal of your threat as well which is unaffected by Spirit Weapons. (note: CL and LB will have a 0.5s reduced cast time without talents, so at max range you can cast CL on-pull before LB reaches the target)
2.) Flurry is a no-brainer! More crits and more dps is always a big deal, especially in 5-mans.
2a.) Stormstrike is then another staple with Flurry, even alongside Spirit Weapons. It provides a bit more dps for the group and more chances at melee crits for your partywide AP boost, Flurry, Focused state as well as overall spot threat for 5-mans. In 5-mans (or possibly for some raid mobs) one can open with Shamanistic Rage, a 2h + Stormstrike and then swap to a shield.
3.) Elemental Focus won’t do much. You’ll likely not land very many spell crits - note that there won’t be world buffs in TBC Classic giving you more spell crit chance. Also Lightning Shield can’t crit unfortunately.
4.) Most other points early on in the enhance tree aren’t going to have as big of an impact as other talents. Lightning Shield is useful on shorter fights but can ultimately be a bigger mana sink than Shocks against bosses for less total immediate dps/threat assuming melee crits, which with enough Agi you should be able to produce. It’s not a bad talent, but if you want to prioritize others you can easily drop it. Improved Guardian Totems will generally do less than Enhancing Totems, as more agi for your party means both more dps and more evasion.
5.) You don’t need Reverberation maxed out, but it is certainly nice to have at least a couple points invested in it. If you can pull with LB->CL (again, both of which will have shorter cast times), SS and ES w/Lightning Shield, keeping up with threat from that point should typically be a non-issue. Also you may often wait a bit longer than 5s to land a melee crit anyway for discounted Shocks.
TLDR: 0/1 Ele. Focus, 0/2 Imp. Weapon Totems, 0~3/3 Imp. Lightning Shield, 0~2/2 Enhancing Totems, 2~4/5 Reverberation, 1/1 Spirit Weapons, 1/1 Stormstrike, 5/5 Flurry.