How to Fix a Stuck Gear Shift on a Keeway K-Light 125

So I have just got myself a new winter project only 2 years old and still in MOT. However there are a few things wrong with it, obviously thats why I bought it!

So far chain is very rusty and some of the chain links are stuck.
Gear shifter is stuck and will not change gear.
Rear Indicator is slightly broken.
Speedo does not work, again another speedo problem to fix.
Brake light does not work when using front brake. This is a strange one as there is no obvious wiring for this.
Brake fluid is slightly yellow.
And a really annoying problem is that the indicators will not always cancel.

Apart from those listed it runs fantastic. Sounds good and looks pretty good too.