Mayellah

Yes, do the flush. It cleans out the entire cooling system. After awhile your coolant loses its protective qualities and needs to be done.  If you can afford it, have it done with a flush machine. If all you do is flush the radiator, your only doing part of the job, but if that’s all you can afford, it’s better than nothing.
 
the only way this might affect your AC is your cooling system may be running warmer than it should, making everything hotter.  The AC system really is not directly connected to your cooling system.

At the very least, learn to do brakes yourself.  There's no reason to touch the calipers unless they're leaking or fully seized.  A 4 corner pad and rotor replacement can be done for $200 USD on the 2011, I don't think it's much more for later versions with the bigger brakes, plus the cost of obtaining appropriate tools if you don't already have them (socket set, jack, stands, wheel chocks, torque wrench, caliper wind back set - combined, you're looking at anywhere from $100 plus renting/borrowing what you need just for that job, $250 if you buy everything, and as much as you want if you buy it from a truck).  Throw in an extra $10 for some sand paper (clean up the surface of the wheel hubs when you change rotors), anti-seize (makes removing the rotor the next time MUCH easier), and some brake grease (lubricate the slide pins - I've had friends with brake problems that were entirely due to the fact that the slide pins were bone dry), you could do the whole thing yourself in an afternoon for under $500 USD.  The next time you'd have to do it, it's only $200, and under $100 if you catch the pads before they wear out.  The way the older models (pre-2012) chew though brakes (single piston front caliper is the tell for the smaller brakes), you should learn to do it yourself.  There are plenty of threads on this topic on this board (and I think one or two where I've posted the torque specs for the associated bolts).

Click image to open expanded view     ACDelco 45K0225 Professional Rear Upper Suspension Control Arm
by ACDelco Be the first to review this item           Price: $90.43 & FREE Shipping. Details  can be found cheaper this is amazon  i paid about $160 for both sides from quick lane they gave me a lifetime warranty on the parts as well

see my above post yes your upper rear control arms are out of spec (camber) NON adjustable you can just replacing them with oem parts but do like i did with aftermarket adj ones way better

Have you consulted your owner's manual?  That will tell you everything you need to know about the maintenance schedule and what items are required based on intervals.
 
https://carmanuals2.com/dodge/journey-2011-owner-s-manual-31045
 
As for the alignment check - did they actually put it on an alignment rack and give you a readout of the current measurements?  If not, how could they possibly know it's out of alignment (unless it's horrifically out of alignment)?

Can’t help you with the cost of plugs,etc. but who gave you the line of crap about the alignment?  I get a 4 wheel alignment every couple years.....about $120 US

i am getting close to 100 k and my local dealership quoted me plugs $89 for 6 plugs labor $210. coolant flush $179 and didnt quote me for a transmission service but my lat one that i did at 60 k was about $180 plus tax on all.... also.... yes the upper rear control arms are NON adjustable the lower ones are adj as is the whole front end is adj as well. i know this as my upper rear were bad and i had them replaced with aftermarket adj control arms about $80 for 2 plus install about $150 also 4 wheel alignment cost about $95. most places i bought a lifetime deal from quick lane (they are owned by ford dealers)cost me $172  every time i have my oil changed and tires rotated at 6 k i have the alignment checked   USA prices and also i would skip the fuel induction service unless you are having problems , i run some chevron fuel inj cleaner thur my tank about 2 times a yr