Size of resume depends on quality of content. If you are educated and experienced person then quality and relevance of content will be considered. If you are a fresh student then you will need enough information to fill just one page only.
You can include your GPA/Grade only if they are high otherwise it will make bad impact. If you have gained B, A, or A+ grades then you can include your grades.
If you have irrelevant experience then you can add it on one condition only if you left some space I your resume. Your relevant experience will always give you plus points in resume.
If you have command over your skills then you should include your computer and language skills.
The most simple without graphical properties but well formatted resume should be adopted.
Not at all you cannot use same resume for different jobs and not even for different levels of same department. Always make resume according to your job or level with maximum relevance of content.
It is not necessary because references are required at interview stage. If you think there is some space left then you can add.
You can make an effective resume by understanding content. www.givemyresume.com helps you in all contents of resume with facts and examples.
You name should be visible in resume with big font size and bold.
You should use abbreviation for your degrees and departments in which you have worked
It not necessary but it makes good impression if you always submit cover letter to resume.
Every single letter format can be used for cover letter without any doubt but left justified text is mostly used for cover letter.
Follow up can be complicated due to your curiosity and passion for a specific post and you have to reveal it without irritating employer. You should follow up to one only.