Which Canon lens should I get for portraits/weddings?

I am new to the world of photography and purchased Canon EOS 600D. Along with that I got the below basic lenses i.e.. the EF-S 18-55mm f/3.5-5.6 and EF 75-300mm f/4-5.6. III.

With these two lenses, I am able to take regular and distant pics. Now what I am also looking for a lens for family portraits, individual portraits and wedding/party pics.... just personal shots and perhaps One lens that I can use to shoot an entire wedding.. may sound a bit optimistic but its just as a secondary photogs.... From my part, rather than shooting qns in air , i have gone thru your articles and some others and shortlisted the following lenses in descending value offer per my very limited undrstanding. Would appreciate if you can please help me in selecting best lens.

1. Canon EF 85mm f/1.8 USM....


2. Canon EF 35mm f/2 (1.4) IS USM Lens – Costly for me, so until it have great value, I will not go for it....


3. Canon EF 100mm f/2.8L IS USM Macro Lens – Costly for me, but if valued i can buy....


4. Canon EF 50mm f/1.4 USM....


5. Canon 50 mm f1.8 – AED 300 (Cheapest, so until its very different form 50mm f1.4, I can go for this).

Also lot of people suggest Canon ES 70-200 f/4L (0r 2.8) – As its a zoom lens, why people are suggesting for even indoor wedding pics also? Or is this better or produce equivalent pics then primes like 85 or 50 mm for portraits and indoor low lights photos also?

Please help, as my couple of days research & plenty of choice has confused me to the core.