Lost two injectors help

[300rwhp]

Details, 2003 F350 6.0 Diesel 173000 kms. early 2003 engine.

So I am really starting to lose my confidence in my truck. Bought it used and had very minor problems until warranty ran out. Since warranty ran out, i have replaced 4 injectors (right bank, only two went but they were in there so had them change the rest). I have gotten death wobble, and corrected it by changing shocks, axle end, hub assembly, sway bar bushings. The injector control pressure sensor has gone and so I replaced it as well. Now after changing my oil ( delo 400) and driving out the the coast the truck ran fine but on the return trip ( 1000kms each way) At about 600kms in I started getting a wobble in the wheel and pedals, thought it was death wobble at first but nope it was injectors. Problem would come and go for the drive until I know I lost at least one. At which point truck would drive fine but plenty of black smoke was coming out the tailpipe.

Got the truck to the closest dealer ( 400k ms of driving with this black smoke situation) and they tell me that I have lost 2 injectors on the left bank. I am going to have the 4 replaced. My questions are as follows;

1. Did driving possibly cause some further problems or trouble that can be mitigated or checked for?
2. After reading similar threads some people mentioned that an oil change was necessary. In this situation having just changed my oil before the trip began and using a good synthetic oil will it be necessary to change the oil, or can i check levels and top up?

3. I am a better safe than sorry person but also dont make a whack of money so what else should i be doing to ensure future peace of mind and a solid truck?

Thanks