Re: Wedding Venues in LA/OC (southern california)
this site might helpful in the search photographers - you’ll probably be able to find a price range to work with - http://www.wpja.com/
for the florists, well you can come up with something yourself, definitely in terms of ideas, but i would not recommend doing them yourself- you’ll have a lot going on and assembling centrepieces will be the last thing you want to do on the night before/the morning of your wedding.
if you have trusted girlfriends and relatives who are willing to help out, then definitely you can explain your ideas, practice a couple of times with them, and then leave it to them to assemble, deliver and set up.
if you’re doing them yourself, try to find a wholesale flower market near you since you’ll be buying flowers in bulk.
the cost of your stage sounds good but i would negotiate so they throw in the stage bouquets too. or you can ask them to do a mix of real flowers and silk flowers to save additionally. letting a vendor know you really like their work but are on a fixed budget and is there any way they can work with you… that worked like a charm for me and the hubs when we were making our rounds! 
$15-$20 a head sounds good for caterers but i’m not in your area so i dont know what the average is there. in the end, it really comes down to the menu you choose. the more items and the more elaborate the items are, the higher the price. again, though, anything is negotiable.
MAC would work if you found a desi makeup artist working for MAC because she’d probably be aware of the intensity of the makeup compared to a gori bride. otherwise, i’d suggest having a trial with your MAC makeup artist of choice, showing them lots of makeup pics of the kind you like in desi brides, and coaching them on the look you’re going for as they work on you. it might be helpful to tell them you’re looking more for fashion photography/runway makeup than for a wedding. or you could save the hassle and find a desi parlour in your area.
and of course, one of the best ways to find a vendor, is to go through recommendations of people you know, and to look up vendors from weddings you’ve attended and loved.
oh, and one last thing, go for cake tastings! its one of the best parts of the whole planning process… most tastings are complimentary and you get some great ideas from shopping around in terms of design and price.
this website www.theknot.com also has a ton of links from your area for vendors, so you might want to check it out too.