Hey there!
I checked out the pictures of your babies (I know the feeling!) and this seems like as classic case of too much worry! Since you're a first time gardener, it is commendable that you are looking after your pumpkins so carefully but first timers usually freak out too much! Ideally, pumpkins should be planted in hills, which means that you mound up a bunch of dirt and plant about five or six plants circumferentially around a four-foot diamater circle. The hills should be about five or six feet apart and rows should be about ten feet apart. You've probably noticed by now how much pumpkin vines need to sprawl, which is why pumpkins are usually planted this way. The dead leaves and stems on your plants seem to just be old leaves. Older leaves naturally yellow and die after a while. Your plants are in fact planted very close to one another but as long as you direct the vines and don't just let them tangle up on one another, your harvest will be fine! I would definitely lay off the chemical pesticides. They are extremely toxic and accumulate in plant tissue and your dirt. Odds are you don't really need it either. Unless you see incontrovertible damage from insects (besides a few munched on leaves, because that's fine), I would DEFINITELY leave out the pesticides. Another issue is using inorganic fertilizers. Vegetable fertilizer is comprised of nitrogen (nitrate ion or ammonium ion), phosphorous, and potassium. On your fertilizer, there should be three numbers. This is your NPK value (nitrogen, phosphorous, potassium in order). Nitrogen is primarily responsible for growing the vegetative structures of the plant, which includes stems and leaves. Nitrogen is most important during the growth phase since strong leaves and stems are necessary. Phosphorous is responsible mostly for root development and is also necessary early on. Potassium however is the most important nutrient after flowering occurs. Potassium is less specifically important than nitrogen and phosphorous because it faciliates a number of plant processes. One of these is setting fruit. If you are fertilizing with a chemical fertilizer that has nitrogen in the 10+ range (such as 21-7-14), this can result in the plants only producing leaves and not really setting fruit too strongly. You shouldn't be fertilizing more than once a month (once every three weeks is the max). This is a common issue with new growers! Also, unless it's raining for more than two days straight and this two day wet-spell occurs once a week, leave the tarp off. Pumpkins need a lot of water and their roots run EXTREMELY deep. I would suggest giving them a deep soak about once a week. Water them so that when you stick your finger all the way into the ground, it should be wet at the tip. I usually get a sprinkler and let it soak them through for about a half an hour or so. Strong root development will only occur if the deeper portion of your soil is wet, which is why deep watering is so important. Strong root development is ESSENTIAL to growing pumpkins too! If you haven't already, scratch around each main pumpkin step and aerate the soil. This will help nutrients, water, and oxygen get to the roots.

Basically, your pumpkins are doing great according to your pictures and you need not worry...just make sure you're not giving them too much love. For next year (although pumpkins shouldn't really be planted in the same spot in sequential years since they suck up a lot of nitrogen) try to incorporate a lot of compost, peat moss, and top soil. These are good organic materials that improve soil condition and help to balance out the soil chemistry.

Good luck!
Joe

Thank you very much for your reply, it helped me a lot and now I'm not worried as much. thanks!