Need to add cord to 11.5KW 240V fryer
Boo?  There's a reason it doesn't have a cord.  First, most such machines are hardwired. 

Second, look closely at the power: 11,500 watts @ 240V (this is a 240V single-phase machine, right?) is 47.916666 (repeating of course) amps.  That's a peculiar number.  Remember that continuous loads must be provisioned for 125% of their rated power.  47.916666 amps x 125% = 59.9 amps.  That's even more peculiar. It's perfectly sized to be provisioned for a 60A circuit, and that is why that size was chosen!

Normal plugs and sockets stop at 50A.  60A plugs and sockets are not common, and not standard.  If they had given you a cord and plug, Murphy would have a surprise for you on setup day. 



The plug in your hands is the obsolete, dangerous NEMA 10-50.  Aside from being too few amps, it's NEMA 10 -- hot-hot-neutral.  Neutral is not ground. You don't need neutral and you do need ground. You could use a NEMA 14 (hot-hot-neutral-ground) or a NEMA 6 (hot-hot-ground) if you can find those in 60A.  But this begs another question. 

When the faire provisions power to your booth, what receptacle do they provide?  Because you need the plug that fits their socket, at the risk of stating the obvious.  So your next step is actually to have a conversation with them about that.  

If the faire is providing you 240V 3-phase, and you have more than one of these fryers, then things just got a lot more complicated. 



Answers: 


The cord is way wrong.  So moot.  
Lugs generally take one wire, a wire being a distinct thing from a cable. Lugs are perfectly able to take stranded wire.  In fact, solid wire is rare in #6. 
Don't carve it up, because you'll be returning it to Lowes for credit.  
You don't buy a solid conductor cord, since there's no such thing - it has to be flexible after all.  Once you figure out which connector the job actually requires, you will surely not find it in a pre-molded cord, but many shops will be happy to build it for you out of a component plug and proper legal cordage, which is cable specifically made to be power cord.  You can do that yourself with the right cordage. A proper electrical supply house can sell you that don't go to Lowes or any big-box; they are incompetent and it's too specialty for them, they will cheerfully sell you a super-wrong thing like #6 SEU-AL.