Bad advice everywhere here!
I think that the math favors javelins and shields over blowpipes due to superior armour save reducing the rate at which they die to normal shooting and magic hits and due to javelins being quick to fire which means there is no penalty for moving and shooting and you have the ability to stand and shoot when charged at short range; with blowpipes the movement penalty and multishot penalty combine with long range means single shot a lot of the time anyway with fewer hits than javs and having to single shot against skirmishers at range a lot often means no poison shots; javs allow you to get up close enough to block something and to screen your other units from BS shooting and charges and yet still stand and shoot when charged
I would not recommend locking yourself in to the blowpipe or javelin camp. In my opinion blowpipes are the obviously best choice, according to others javelins are the obvious best choice. Glue the skinks to their bases and don't attach arms until you play some games and familiarize yourself with the trade offs.
20 to 40 saurus (Note: there is a debate over handweapon shield v spear and shield options, HW+shield gives a parry save to the front which means a bit fewer die in combat but spears give an extra rank of attacks which means saurus will wound more enemies in combat)
I would wait for the FAQ before modelling Saurus with Spears. If Predatory Fighter doesn't work on supporting attacks (as RAW would imply) they aren't worth it imo. Spear versus hand weapons is also a unit size preference decision as any time your unit has less than 11 models remaining you will wish you took the hand weapons.
Perhaps, but mounted on Terradons? Stegadons? Or forsake the chiefs for priests? No decision for a new player.
1-2 oldblood (keep modular for handweapon shield or great weapon no shield options)
Totally disagree. I think an Oldblood is far from an auto-choice.
6-10 cold one riders
3-6 Krox
Also controversial units.
Maybe:
1-2 stegadons (build as ancient steg but keep howdah on top flexible to play as reg steg or EOTG as you desire)
1 bastiladon
3-6 ripperdactyls/terradons
for fun consider a carnosaur model with option as scar vet or oldblood on top (I prefer scar vet due to using slaan in lord slot with high magic to recover wounds on carnosaur if possbile)
1 convertion of a palanquin for skink priest (40mm by 40 mm square) for possilbe use of Tetto special character in fun games and where special characters are allowed
I however would say 1 Steg and 3 Terradons are definite inclusions not maybes.
I also suggest you buy a Saurus oldblood model because he is probably the most survivable lord/hero for the points cost.
Combat characters look cool but they have very specific uses in the actual wargame. Would not recommend if trying to be frugal with your model budget.
Now onto my actual suggestions:
I would avoid the Battalion. The Saurus Cav are dead money and the Temple Guard are rediculously expensive and IMO are better for a conversion project down the line (easy to turn Saurus Warrior Spear arms into halberds and if you pool all your trinkets from the Warrior sprues they can look elite).
I think the only definites are:
2 boxes of 24 Skinks
2 boxes of 16 Saurus
1 box of 3 Terradons
1 Stegadon (don't glue the giant bow, blow pipes, engine or any models to the top)
1 Slann
Buy that, have some fun with some little games. Proxy Skinks as Chameleons and Saurus and Temple Guard. Finish painting and modelling all but 15 skinks and maybe a few Saurus (maybe you want to convert them to Chameleons or Temple Guard). Then try to write a 2000 point list. Think about it a bit more, then buy what you need to make the 2000 point list.