Well, HELLO, Ketchum88 and WELCOME to FR-S ownership and ..... The Forum .......
WOW - you sure picked a pretty one ...... looks clean too ......
I'll take your question about an arm rest literally and suggest there are several aftermarket ones available.
The one I use is shown below. It is more of an "elbow" rest and will accomodate both mrs humfrz and my elbows (without touching). After 30 years of marriage .... touching ain't what it used to be ....
It's from another application, (modified) by me.
As far as modifications, stay tuned, these folks will turn you on to all kinds of neat stuff. Personally, I would recommend you consider a shark-fin type of antennea and a set of OEM splash guards (mud flaps). Then you will be good to go.
Just read the owners manual ...... TWICE, two weeks apart, keep your distance from parking stops, fill it up with high-test gas and hit the road for some fun driving!
humfrz