Need Help For Standard Visitor Visa!!!

Please excuse my poor English.

I’m Malaysian and 24 years old. I was refused to enter to UK on 23rd March due to frequent visits & successive visits in the UK in 2017. The entry clearance officer advised me to make a visa before my next visit to UK. I had a big crossover
23rd March, it was my fifth time to travel to UK. The main purpose of travelling UK is to visit my partner & sightseeing in the UK & travel to other Europe countries.

I came to UK on 23rd March 17 and left on 28 July to Malaysia in 2017. During this period, I’ve made several trips to Europe because we love travelling. After I return to my home country on 28 July, I travelled to UK again on 4 Oct and left on 13 Dec 2017. During this period, I’ve travelled around in the UK for sightseeing and Amsterdam as well. After I returned home country on 13 Dec, I travelled to UK again on Jan and returned on 9 Feb this year. During this period I had travelled to Iceland with my partner. I had never stopped by the UK Border because my partner accompanied me all the time, unfortunately he failed to accompany this time. We’ve no well knowledge about Immigration rules until this things happened. From 23rd March 2017 to 23 March 2018, I had spent 212 out of 365 days in the UK.

I’m not financial independent because I’m unemployed since the day I graduated in November 2016. I’ve savings which is 4,400 pounds in my account. My father covered all my expenses when I’m in Malaysia. My partner sponsored and accommodated me all the time when I was in the UK. His mother is willing to sponsor me as well because she used to encourage us to travel more when we’re young.

I plan to travel on 20 April and return on 28 June

I’m able to show evidence as my supporting documents as my
building society book;
original bank statements which including my partner, father and his mother;
sponsor letter from my father and his mother;
invitation and sponsor letter from my partner;
certified copy of my partner’s birth certificate, passport, brp card and student id;
travel itinerary ( I plan to travel to Budapest, Athens, Mykonos, Santorini, Spain and Portugal);
original tenancy;
return flight ticket;

I wanna ask,

1. Is there any consequences if I overstayed in the UK?
2. I’ve done the research and stated that it would be fine as long as I leave before 90 days voluntery. Is it real?
3. Do I need a lawyer to represent me to apply for the Visa as I was refused to enter to the UK?
4. Do I have to provide a letter from my partner’s landlord in order to prove I’m allowed to stay in the place?
5. How can I show the strong ties to my country as I’m unemployed now? For example, a job offer or study offer? I can look for a job or continue my Master because I’m desperate to travel to UK and other Europe countries as I listed above.

I need guidance and advice regard to case. Thank you.