Couple questions - diesel lines & coolant

[amcarreon]

I just noticed my diesel lines are leaking underneath the engine, how big of a repair are we talking about here? There are two leaks from what I can tell, pretty steady too. I'm hesitant to take on a big repair myself because I am new to working on my truck.

Last week I found that my lower radiator hose clamp came loose at the engine connection and I'm assuming the pressure blew the hose off. Needless to say I lost all my coolant (or so I thought lol) and so I re-clamped the hose, then went to refill my system back up. However, dumb me... I forgot to drop the hose from the radiator side and make sure that my system was completely empty. Well, 2.5 gallons of coolant later I'm noticing its getting full.. so now I just cost myself about $50 in coolant ($16+tax per gallon @ Ford) because my coolant is in now way 50/50 now! So to justify myself spending another $50 on coolant, I want to verify its a bad idea to have a super concentrated amount of coolant in the truck. I'm going to drain the system anyway, because I don't want to cause some other issue down the road over saving 50 bucks.

edit: Do I need to do a flush on the system as well?