Student 10 years ILR application advise

[bethuk]

Hi everyone.
I became 10 years 19th May 2018. And my student tier 4 visa is until May 2019. I have few questions. I am an undergraduate student. I will graduate around 2020 instead of 2019. because I carried my study under sickness and recently hospital and GP digonised my sickness and started treatment. With medical evidence, university agreed to provide repeating second year with teaching. Before I apply I LR, I have few questions.
(1) I left UK on 25/10/2015 (visa expired date 26/10/2015) for applying new visa and uncompleted documents with university. I came back 19/1/2016 with new visa. In this point, when I left uk, i did not get any stamp from UK and even in my country when I arrrived. How could I prove in this case?
(2) I am really want to finish my study at 2020. But if my ILR application is not succeed, then it would be effect to whole my study period as my visa remained a year yet. Is it okay apply ILR now or later? Any advise?
(3) I changed my place of birth (town) at last application. Because I could find out that my ex application place of birth was different with recorded place. My country system recently upgraded as computer so that I could check now information clearly but before I should rely on by parents's memory. And my parents remembered registration place of birth instead of recored place. I even did not born there, our tradition need to be recorded as father's origin. Actually, birth place is not important information in my country system. How should I dealing with? Will it important to consider ILR?
(4) I will be a student when I apply ILR, what document do I need to provide?
Thank you.
P.S if I use a lawyer, will ot increase to succed my application? Any recommanded lawyer, not expensive too much.