As a new (very!) small business, the IRS has lots of advice and information for you. Start at https://www.irs.gov/businesses/small-businesses-self-employed and be sure you have several pots of coffee or other appropriate aid against somnolence.
By default a single-member LLC is 'disregarded' for tax purposes (at least for Federal, and generally states follow Federal although I don't know Mass. specifically), although it does have other effects. If you go this route you simply include the business income and expenses on Schedule C as part of your individual return on 1040, and the net SE income is included along with your other income (if any) in computing your tax. TurboTax or similar software should handle this for you, although you may need a premium version that costs a little more.
You can 'elect' to have the LLC taxed as a corporation by filing form 8832, see https://www.irs.gov/businesses/small-businesses-self-employed/limited-liability-company-llc . In principle you are supposed to do this when the entity is 'formed', but in practice AIUI if you do it by the end of the year they won't care at all, and if you do it after the end of the year but before or with your first affected return you qualify for automatic 'relief'. However, deciding how to divide the business income/profits into 'reasonable pay' to yourself versus 'dividends' is more complicated, and filling out corporation tax returns in addition to your individual return (which is still required) is more work, in addition to the work and cost of filing and reporting the LLC itself to your state of choice. Unless/until you make something like $50k-100k a year this probably isn't worth it.
1099 Reporting. Stripe qualifies as a 'payment network' and under a recent law payment networks must annually report to IRS (and copy to you) on form 1099-K if your account exceeds certain thresholds; see https://support.stripe.com/questions/will-i-receive-a-1099-k-and-what-do-i-do-with-it
. Note you are still legally required to report and pay tax on your SE income even if you aren't covered by 1099-K (or other) reporting.
Self-employment tax. As a self-employed person (if the LLC is disregarded) you have to pay 'SE' tax that is effectively equivalent to the 'FICA' taxes that would be paid by your employer and you as an employee combined. This is 12.4% for Social Security unless/until your total earned income exceeds a cap (for 2017 $127,200, adjusted yearly for inflation), and 2.9% for Medicare with no limit (plus 'Additional Medicare' tax if you exceed a higher threshold and it isn't 'repealed and replaced'). If the LLC elects corporation status it has to pay you reasonable wages for your services, and withhold+pay FICA on those wages like any other employer.
Estimated payments. You are required to pay most of your individual income tax, and SE tax if applicable, during the year (generally 90% of your tax or your tax minus $1,000 whichever is less). Most wage-earners don't notice this because it happens automatically through payroll withholding, but as self-employed you are responsible for making sufficient and timely estimated payments, and will owe a penalty if you don't. However, since this is your first year you may have a 'safe harbor'; if you also have income from an employer (reported on W-2, with withholding) and that withholding is sufficent to pay last year's tax, then you are exempt from the 'underpayment' penalty for this year.
If you elect corporation status then the corporation (which is really just you) must always make timely payments of withheld amounts, according to one of several different schedules that may apply depending on the amounts; I believe it also must make estimated payments for its own liability, if any, but I'm not familiar with that part.
