I'll leave someone else to respond to your other questions, but regarding a FLR(FP) application, as you have no spouse or children in the UK, the only sub-category would be FLR(FP) Private Life.
However, from the information given in your post, it's doubtful that you would qualify. See the following from Part 7 of the Immigration Rules:
Private Life
Requirements to be met by an applicant for leave to remain on the grounds of private life
276ADE (1). The requirements to be met by an applicant for leave to remain on the grounds of private life in the UK are that at the date of application, the applicant:
(i) does not fall for refusal under any of the grounds in Section S-LTR 1.2 to S-LTR 2.3. and S-LTR.3.1. to S-LTR.4.5. in Appendix FM; and
(ii) has made a valid application for leave to remain on the grounds of private life in the UK; and
(iii) has lived continuously in the UK for at least 20 years (discounting any period of imprisonment); or
(iv) is under the age of 18 years and has lived continuously in the UK for at least 7 years (discounting any period of imprisonment) and it would not be reasonable to expect the applicant to leave the UK; or
(v) is aged 18 years or above and under 25 years and has spent at least half of his life living continuously in the UK (discounting any period of imprisonment); or
(vi) subject to sub-paragraph (2), is aged 18 years or above, has lived continuously in the UK for less than 20 years (discounting any period of imprisonment) but there would be very significant obstacles to the applicant’s integration into the country to which he would have to go if required to leave the UK.
Be aware of the fact that if you submit a FLR(FP) application simply to buy time which you know will be refused, your application could be considered as 'frustrating the intentions of the Immigration Rules as 'vexatious and frivolous' and liable for a refusal under 320(11).
See RFL7.3 What are aggravating circumstances
https://www.gov.uk/government/publicati ... raph-32011
This would adversely affect visa applications in the future.