There was a small spike, but I dont think it was an attack or stress test. Looks more like higher usage.
I prefer -> https://statoshi.info/dashboard/db/transactions
now that my node can no longer handle all TX, it can only give you a rough picture -> http://213.165.91.169/
No. For one bc.i (same as my node now) restricts which transactions they accept. Its also possible that there are 2500 "legit" transactions waiting for a confirmation. Bitcoin is still used differently around the world which results in times where there are more TX. Like a rush hour.
It gives you a recommendation in satoshi per byte. You can roughly estimate 10 byte base + 180 bytes per input and 34 byte per output. Depending on the wallet you use it might not be possible to know how many inputs are used though.
No, the blue line is the number of unconfirmed transactions. If its constantly high there has been spam in the past. If its increasing over a longer period there is currently spam going on. Keep in mind the 3rd graph for malleated TX. The more red you see the more TX are malleated.
IMHO the best solution is to run core as it estimates the fee based on the current state of the network. I know of no other wallet that does this. For every other wallet you have to either go the easy route and take a rough rule of thumb that might result in a "too high" fee or do the estimate yourself everytime. I would argue that its not worth anyones time to check different pages for 10-15 minutes in order to safe a few satoshi in fees.