Roll Tiges: Welcome to Autopia!!
I have bad news for you concerning your bug-embedded "stains" on a painted bumper. They are more likely "etched", meaning a chemical reaction has occurred between the bug guts that were allowed to stay on the paint surface for an extended period of time and bumper paint. It has literally "burned" (etched) the paint (clear coat, actually) and if it is a light etch it MIGHT some out with some machine compounding OR require some serious wet-sanding to mitigate that "stained" appearance. Not something a novice can easily do. Deep etching required a repaint of the area to "fix" it.
As far as a product to remove bugs, I`ve used
Poorboy`s World Bug Squash. It works very well at "dissolving" bugs without requiring excessive rubbing with a bug pad that will scratch/swirl/marr clear coated paint. The important thing to do is to remove bugs as soon as possible and not let them dwell on painted exterior surfaces for extended periods of time (more than a week). Grasshopper guts are the worst and any moisture (humid days or rain) will accelerate the etching. Bird dropping are even worse. Seagulls and Canadian Geese droppings are horrible and should be removed that same day, even if it just spot washing.
As far as leather care, there are a lot of different products to use. I would suggest
Griot`s Garage 3-in-1 Leather Care Creme (NOT the liquid spray!) for something easy and effective for your leather care.
If you want something a lot "better", but more expensive, look at
Colourlock Leather Care.
More forum thread info on leather care, please see:
https://www.autopia.org/forums/car-d...hlight=leather
See post #54 from Stokdgs about Spinnybeck Leather Care products!!!!
Want to know the latest about what to apply to an exterior paint, sometimes referred to as a Last-Step Product or its acronym LSP, see the recent thread discussion on graphene coatings: (Very lengthy, but great info on this new product development!)
https://www.autopia.org/forums/detailing-product-reviews/191707-graphene-coatings.html