Yes you need a bigger compressor but again it drains the power of your engine.
So if you are ok with the loss in pickup, then try sanden 508(i guess,forgot the exact model).
Yes people don't threat properly when we take our 800, I too faced this problems.
But now, any thing either mechanical or electrical I will only do it. But I have an good local mechanic for my assistance.
For head lamps you can go for 100/90 blubs with relay and wiring cost 1k
Horn its upto you starting from 500rs, I have hella redgrills cost 1350 a pair.
Also if you put 100/90 bulbs, please dont use any other electrical accessories with it because our 800's stock alternator does not have the capacity to charge the battery.
I have upgraded to swift alternator. Please refer this thread, DIY Alternator Upgrade of Maruti 800