How many days will you be gone will depend on how much you pack. One rule of thumb is to pack half the number of shirts and pants for the number of days you will be gone. Of course the exception to that is underwear. One per day for that. Example you will be gone 8 days, then pack 4 shirts, 4 pants and 8 pairs of underwear. If you will be gone for a few weeks, then pack 7 of each. Many hotels, particularly on a military base, have a wash room for visitors. Also most gas stations have travel sized laundry detergent packs. If you have a special event such as a wedding, then do not include that outfit in your number of shirts and pants or skirts.
If you know you will be giving and receiving gifts that will be in large enough quantity to have their own checked bag, ship them to your destination. Even most hotels will hold packages at the desk for you as long as you notify them that they are being sent.