UK visitor visa: sponsors and itinerary on visa application

I've been reading this forum and trying to learn as much as I can from other questions. But I still feel like I need to post my questions here. Hopefully, my explanation and questions are clear enough and not a repeated question.

I am an Indonesian, recently graduated from a UK university. I finished my studies in September 2017, but moved back to Indonesia in January 2018 (My past Tier 4 Student Visa allowed me to stay for another 4 months after I finished the study).

I plan to visit the UK for multiple purposes for 2 months and 9 days (June 4 - Aug 13): to attend my graduation, to have 2 separate family holidays, and to visit friends and my English boyfriend.

ITINERARY

Here is my planned itinerary:

• 4-23 June: Holiday, visiting friends & boyfriend
• 24 - 29 June: Accompanying sister's holiday in London
• 30 June - 8 July: Holiday, visiting friends & boyfriend
• 9 - 17 July: Holiday with parents and auntie in London and other Schengen countries (I will apply for the visa after getting the UK visa)
• 18 - 19 July: preparation and graduation day
• 20 - 25 July: holiday with parents and auntie in the UK
• 26 July - 13 August: holiday, visiting friend & boyfriend

I have made a dummy itinerary, hotel bookings with free cancellation, travelling around the UK. While in reality, I am planning to stay with my boyfriend while also take some holidays with family and friends.

Should I state my visit will be until 13th of August or coming back with my parents on July 25th to reduce the expense and lessen the stay on the application and look more genuine?

SPONSORSHIP:

1. Accommodation

I have a Greek friend from school who will sponsor my accommodation while in Manchester for the days I'm staying without my family (they plan to attend my graduation as well). She is currently working and living in Manchester.

I thought that having her sponsor my accommodation instead of my boyfriend would imply that I have no reason to overstay or going underground in the UK (although I genuinely have no intention to do so).

Do I need to attach her bank statement although she will just sponsor the accommodation?

Is it the right move or should I just use my boyfriend's accommodation (we've been together for 9 months in person and 2 months in a long-distance relationship after I moved back to Indonesia. I have proof of emails, WA chats and pictures to proof genuine relationship)?

2. Finance I have around £5,450 in my bank account (from my previous salary in Indonesia, parents' allowance during my studies in the UK and my salary during the internship year in the UK), but with a 2-month and 9-day visit, being unemployed, I don't think they will see it as a sufficient amount or promising. So both of my parents and my sister agreed on partially sponsoring my expenses.

Will multiple sponsorships on accommodation and finance work?

TIES TO HOME COUNTRY

I did a project based work on Feb - March 2018 and currently waiting for the bidding result on the project I worked on. If I the bid agreed, I would have a job by August 2018 (after I return). The result should be out by the first 2 weeks of April. Until then, I am still unemployed.

Should I ask my potential employer to issue this potential employment or wait until I receive the result and apply for the visa?

My parents bought a flat under my name to be rented. Could I use the documents as proof of ties to home country although it was bought and maintained by them?

Other documents I have:

1. Graduation invitation letter from University and previous student letter
2. Letter of accommodation sponsorship from my Greek friend, including her passport, payslip, bank statement and tenancy agreement.
3. Letter of financial sponsorship from my parents and sister, including family card (to certify genuine family ties) and their bank statements.

Please if any of you could kindly answer these questions, it would be much appreciated!