Filter = Yes a synthetic media filter will be capable of filtering down to a much lower micron rating - so yes better performance!
Oil = Huge can of worms here!
Conventional oil will be easier on your wallet - that is about it.
With rebates - Synthetic oils have closed this gap.
As for performance - I feel synthetic oils can/do handle the heat & cold cycles more efficiently! (A LOT of technical info falls into this subject)
In extremely cold temps - Synthetic oils have proven to have a flow & pump ability advantage.
As for Lubrication Properties - I feel it's a wash!
Tons of UOA have proven neither Conventional nor Synthetic has a True advantage here!
I feel choosing the right viscosity is much more important!
Normally this is decided by just how **** the owner is.
Towing - If you choose conventional oil - I would have short OCIs.
(3-5K miles)
If you choose a synthetic oil - you can possibly extend your OCIs.
(6-8K mikes)
But I would definitely only run a high quality synthetic media oil filter no matter what type of oil you choose.
Mind you: This does not take into consideration the cam/Lifter issue that has plagued the 5.7L - Visit the synthetic oil thread - posted within the engine/performance section.
SyN Disclaimer: This is only my one sided opinion gained from over 37 yrs of worrying about oil & lubrication.
Prepare yourself to receive MANY types of difference of opinions on this subject!
Don't be persuaded by those who preach - Use what I use because I use it!
Your best bet is to choose a combo & after 4-6K miles do a UOA.
Then switch to another combo & do a UOA.
Your 5.7L believe it or not is going to react differently to different combos when compared to others due YOUR different driving style/habits.
Fuel economy: All depends on the driver & the total mechanical condition of the truck.
Good Luck to you - This subject has Never had a clear simple answer.