IELTS

You cannot get admission in any country to pursue MBA without the IELTS score.

Yes, you can, but if you want to study in good German Universities, you have to score 6.5 or higher in IELTS.

Yes, as most of the universities need to know your competencies in English and it becomes easier for visa interview.

I am sorry, IELTS band of 4.5 is too low. You need at least 6 band, preferably 6.5 bands minimum to pursue any course at decent university abroad. With your score, your visa will get rejected.

Dear Khurminath,
Germany is the best country for mechanical engineering but your academic grades are not at par with German universities. USA on the other hand has the maximum universities which are globally known, you can check out university options in US, Australia and UK for your studies.
Remember to study in US you must take GRE. You must also take a look at the entry requirements for all universities you wish to apply to as they differ.
Best of luck.

Yes, you can get admission.

Hi,
Kindly, check the listing on Shiksha website:
https://testprep.shiksha.com/ielts-exams-coaching-classes-in-delhi-ncr-categorypage-14-51-930-0-0-10223-1-2-0-none-1-0#cateSearchBlock

Of course, IELTS is accepted by UK and many countries, in fact preferred in UK. London for your information is not a country so you need to be specific where you want to apply. Canada is a better option as it offers work permits which is not available to international students in UK currently if you have been following updates and news closely. Nevertheless, you must narrow down your choice basis the university requirements, budget, climate etc. and select where to study.

Yes you can provide your IELTS scores for admission purposes, but check with the university website once if they accept IELTS scores or not. Most universities do accept them, so you should be fine.

5 band is a little low score. Even if you get accepted to a university with this score, you might face problems during your visa interview as the visa official may reject your application based on your IELTS band.