If I was starting wow from scratch, on a new server not knowing anyone...

Definitely go the recruit a friend route. You'll level so much faster.

You'll be strapped for in-game gold along the way, so have skinning on one of your support toons.
(You can make a two line macro 1) /targetlastenemy 2) /use skinning(apprentice)
Go with both mining and herbalism on your main/most active toon.
That way, you're at least gathering all the way up. Take the time to level these skills, they're decent money makers.
One member on your team should be an enchanter for disenchants down the road.
Any skill beyond skinning, mining and herbalism will cost you to level them, but can make you something down the road.
*edit* Pick the most important skills leveling up. Give each shaman an up to date Lightning Bolt, Lesser healing wave, maybe skip a lot of spells depending on gold. For the paladin, take anything that is good for tanking.

I'd go with... Paladin tank and 4x shaman's. Pally is the active toon most of the time.
Shaman's are spec'd elemental for dps. For the most part, their dps is something like this:
1) assist the paladin -and- 2) cast offensive spell.
You can use a focus based assist method, but a party leader will leave you focus for other things.

Down the road (or with dual-specs), you might want to spec one of the shaman's resto for heroics.
No need for resto leveling up. Elemental can heal just fine.
Basically use your assist method, target whoever needs a heal and cast the heal.
Four healing stream totems is a lot of heals.

Shammies will have a totem stomping macro, which is a key with a castsequence on it.
Each shaman has Fire, Water, Air and Earth (initially just Earth I believe, but you add others as you level).
So pressing the key will be, /castsequence reset=5 Fire Totem, Air Totem, Earth Totem, Water Totem.
Just look at your available totems and try to have as many useful totems down at once.
A lot of them stack, the ones that don't have one of each useful type at once.

Also have access to dropping totems outside of the sequence is helpful.
For example, I can drop 4x Healing Stream, Mana Spring, Searing, Magma, Grounding, Poison/Disease Cleansing (two of each), or Tremor Totems on a click.
Decide what is useful to you and go with it.
It's not like you cannot fairly easily adapt to it.

Read what works for others and try anything you'd like.
You'll find a system that works for you and maybe contribute a bit down the road to others.
This is a phenominal community.