f you are resolute on making this trip happen then you will enjoy yourself regardless. If you are open to advice, I offer mine.
Mike C will tell you sooner than me that a trash compactor bag is a light, waterproof solution for waterproofing the entire contents of your pack, and cheap. Leave the pack cover at home/ or do not buy.
If you have money to spend on boots/a sleeping pad etc. I would argue to change what you are looking at.
I own the powermatics; I like them when I am going to be doing a lot of cross country day hiking and places with very unstable ground. I can't recommend them for a backpacking trip. They are also over $200 so a really big investment.
The neoair is a great pad but also expensive at over $100.
If I were in your shoes and knew what I knew now, and what I had, I would spend my money differently. I would look to buying a lighter shelter on the cheap. A tarp and bug net are light and easy to deal with.
This equinox tarp offers a ton of coverage at a low weight. You could combine it with granite gears the haven for a large, ventilated, bug free dry zone. Also you would save about 3 pounds of weight.
If you can get your pack under 30 pounds fully loaded you should be able to use trail runners, unless of course you have pre-existing ankle problems. They are lighter, more comfortable, and cheaper than the heavy boots.
While not as light or new as the neoair the big agnes insulated air core, or poe ether thermo 6 are also great, comfortable, relatively light and more affordable alternatives often found on sale.
As for trekking poles, you can find some amazing poles in the over $100 range from gossamer gear or tigoat. If you are looking to spend less though you can get decently light pairs from rei outlet for around $50.
As for cooking lunch on the trail, it depends on the group and people, there is no right or wrong way to do it. I will say however, if you are planning on using a stove at lunch a white gas stove will take more time and effort to prime and prep, maybe often leading to it not being used at all!
As for the first aid kit, if it makes you more comfortable than bring it. Having the knowledge to use its contents is the least you owe yourself though if you are going to be carrying it on your back for miles. You may find that its contents are redundant and you could get away with some band aids, ibuprofen, Benadryl, and leukotape.
The golite reed pants are the standard round these parts for rain bottoms.
If you are going to have an umbrella you should be able to leave the rain jacket at home and instead bring a wind jacket, much lighter, and more flexible for most situations.
If four people are going you should be able to split up gear among all of you. You don't each need your own tent/stove/first aid kit/etc. This advice comes from not just me but the countless others who have learned what I have. The lighter you can make your pack the more enjoyable your hiking will be. You should not sacrifice anything in terms of comfort by making these changes.