TIER 2 General - Different SOC code with same Employer

[krishin4u]

Hello Guys
Currently I'm working as a software tester with soc code 2139 and annual salary is 32k, I got an extension recently. I'm planning to change my career from tester(2139) to developer(2136) with the same employer.
If someone could help me out in few questions that would be very helpful.

1. Do I need to apply visa with new soc code(2136) ?
2. Am I eligible to work with 2139 code as a developer, as I already got visa till 2019 ?
3 . I know that's not possible to work with different job code, any suggestions ?
4 . I will be eligible for ILR in sept 2018, does this role change might effect in ILR process ?

Please Help me out !!!

Thanks
krish