Hand-written papers are rarely accepted. For almost all classes, you should plan to type or word-process your document. Smaller font is too hard to read, especially if your readers are reading 100s of pages a week. Larger font may look like you are trying to pad the length of your document. Depending on your professor's preferences, you can indent or not indent your paragraphs.
Some professors like to read work that is double-spaced.
At a minimum, include additional white space between paragraphs to make these separate thoughts stand out on the page. Some people think single spaced text with ample white space to mark the paragraphs and no indentation of the individual paragraphs looks more professional than double-spacing or indenting. Single spacing uses less paper overall. Please staple pages together. Unstapled papers are unprofessional and extremely irritating to handle in the workplace.