This is an area that interior painters can easily cut short to save time. Most contracts don't state the extent of the wall repairs included, so it's up to the painter's discretion how much they will do. If it seems like too much work, they'll usually point out the repairs but don't include it in the bid. They'll then ask you if you'd like it fixed after they start your project and let you know how much more it will cost.
The cost to paint metal siding -- most commonly aluminum and galvanized steel -- will depend on a variety of factors. In some instances, a simple cleaning will suffice to prepare metal siding for painting. In worst cases, painting professionals will need to repair metal that is rusted, damaged or missing pieces due to climate conditions. In the case of severe damage, a professional will have to remove the old finish and paint to get to the original layer, which will add on to the final price. When you add the actual painting of the metal siding, you might be looking at a final bill between $400 (~250 sq. ft.) and $1,500 (~1,000 sq. ft.).
You have lots of options available at an even wider variety of price points. For your online marketing, you need to take your website, social media management, pay per click services, online review management, email marketing, and local business optimization services. Offline - there are even more options like direct mail / print marketing, home show appearances, yard signs, etc.
If the point of hiring a well established, experienced, reputable painting contractor is to secure the professionalism and trust suggested to be inherent with that choice, then I would EXPECT that professionalism and experience to include the ability to make the proper and correct calculations for labor and materials for a fixed price quote, and there should be NO reason for the contractor to put the cost burden of their miscalculation on the consumer.