Some help for a noob?

[Rory]

Hi! I'ma new player about to start their second campaign on 3.5e and ever (the first one was a evil campaign, not the best to learn) and first time I try a spellcaster class.
I'll be a chaos gnome cleric/warlock with then the prestige class of eldritch disciple, chaos/trickery domains (to summarize, I should PEW PEW heals to my allies and yes, I know I didn't exactly choose the easiest thing around).
I'm fine enough with spells, but I'm a bit of lost for equipment and how I should roleplay my character.
My master has set 15k gold coins we can spend in any amout we want to prepare ourselves before the campagin starts and I don't know what to buy, keeping in mind that I should save some gold for later possible use.
Aside from that, I need some general tips to make it work as good as I can.

EDIT: I should add that my team has, beside me, a mage, a bard, a barbarian (I think?) and a thief.

[BowStreetRunner]

I played an eldritch disciple a while back and one of the big equipment questions I had to deal with was what armor to wear. It basically comes down to evaluating how good is your Dexterity, do you want to put feats/spells into defense or just put it into armor, and what penalties are you willing to put up with from wearing the armor.

Mithral Full Plate is an excellent option (+8 AC, Max Dex bonus +3, -3 Armor Check Penalty, Speed 15 for a gnome) You don't have to worry about arcane spell failure, and the Max Dex bonus is high enough to get the most out of even a 16 Dex. If you are planning on using Balance, Climb, Escape Artist, Hide, Jump, Move Silently, Sleight of Hand, or Tumble heavily you do have a -3 check penalty (-6 for swim), but of those only Jump is a class skill and I don't imagine that is a major priority, particularly if you pick up Fell Flight. The 5 ft hit to your land speed will still impact Fell Flight since its speed is based off your land speed, so something that gives an enhancement bonus to movement is recommended as another equipment option.

It's really a matter of how much you want to invest in it right now. Eventually it's likely to be something you want to pick up. I usually would go with either Glamered or Called armor, or both so that I didn't always walk into every scene looking like a tank.

Chasuble of Fell Power is a nice 1d6 boost to your eldritch blast, so may be worth considering. I had a Greater Chasuble for 2d6, but that is a bit pricey at this stage for you.