Your post makes zero sense. What are you talking about?

If you don't currently know how to code in Swift and SwiftUI then you can either employ someone to do this for you, or just knuckle down and learn for yourself. It's not that difficult. Apple has tons of sample code that you can start using. Have you even tried? If not, then please do so! No one here is going to know how much it would cost to work with someone to implement your ideas, so it's pointless to ask us here. This isn't really the place to ask such a wide-ranging question. We're just developers writing apps for Apple's platforms, and we don't talk about money and costs on these forums. This isn't the place for that kind of thing.

Not entirely sure what your issue is here. You say something crashes, but you don't explain what the crash is, so it's not possible to see whether you're doing something wrong or if there is a genuine issue in Apple's code. You haven't provided any code whatsoever, so I really can't give you any help at all. Can you provide some code that explains your issue properly?

Blue chat bubbles are part of the design language for the Messages app, and besides that, they have the effect of showing you that a message is an iMessage not an SMS, so they're instantly recognisable as an Apple iMessage and it's unlikely that Apple will change this. You could suggest that all received messages could be whatever colour you choose, say black background with white text, but that loses the differentiation between the message types. However, you could suggest to Apple that you should be able to change the colours based on the type of message, e.g. you might want orange with black text for an SMS, and purple with white text for an iMessage, thus keeping the differentiation. It could be not only for aesthetic purposes but also because of a visual requirement, and perhaps they'l allow such customisations. Colour blindness is already covered in Accessibility settings, but it doesn't allow the changing of the bubbles as you'd like. You can make suggestions here: https://feedbackassistant.apple.com/

I see: iOS 18.5 (18.5 - 22F77) - com.apple.CoreSimulator.SimRuntime.iOS-18-5 so that's why mine works fine. I wonder if you can copy that file from somewhere else and put it into where it's supposed to be? Bit of a hack, but according to the internet people were doing this to fix this specific error. Personally, I would remove the runtimes via Xcode, uninstall Xcode, remove the Developer folder in Finder (take any necessary backups), reboot, reinstall Xcode 16.4, reinstall iOS 18.5 and try again. It's a lot, but it should leave it all fresh.

I think you want to use something like SMAppService. Are you saying you don't ever want a UI, or that no UI will be displayed when the app launches? So you'll still have some sort of Preferences UI somewhere? Then yes, use SwiftUI and Swift. Investigate SMAppService.

Can you provide your code for one of the tips that's appearing as a full sheet instead of a popover? Maybe there's something you're doing or not doing in your code?

I have the same setup as you: Xcode 16.4 with iOS 18.5, installed Xcode 26 beta 3, and my iOS 18.5 was removed. However, when I closed Xcode 26, opened Xcode 16.4 and opened one of my projects, the run destination in the project window was an iOS 18.5 simulator but it said iOS 18.5 wasn't installed. I just clicked Get in the Xcode Settings > Components window and it all worked fine. Can you open Disk Utility and look in the left-hand pane? At the bottom is a "Disk Images" section. I have "iOS 18.5 Simulator Bundle" and "iOS 18.5 Simulator" there, and they're both mounted. Maybe you've got the runtimes installed but somehow they aren't mounted?

I gave you the link to the Contact Us page. Click it, use the options to get the phone number for your country. It's not difficult.

Right, well, information like that should be provided upfront so we can offer appropriate help. Okay, what size screenshots for an iPad do you have? You could always use a smaller image, like one for the 11-inch iPad, and scale it up to the right dimensions. Or, you could make an image that fits the 13-inch size requirements but contains the 11-inch image instead. Think of a gradient coloured background with an image of an 11-inch iPad showing your app, and having some text at the top or bottom. Take a look at other apps on the Store, and see what they do with their screenshots.

You should probably use the Contact Us link in the footer: https://developer.apple.com/contact/ It'll give you more options than just raising a post in here. We're just random developers like you.

Are you trying to sign up and pay for an Apple Developer account? Have you tried the Contact Us page listed at the bottom of every page on here? https://developer.apple.com/contact/ There are phone options.

Can't you just use the iPad 13 Simulator via Xcode?

I've got an iPhone 13 mini on iOS 26 beta 3, and the search field is at the bottom of the screen. If it's definitely not there on the iPhone 15 Pro, then you should raise a bug in the usual way at: https://feedbackassistant.apple.com/ then post the FB number here.

Given you're now back on iOS 18.5, this is not an issue in the beta. Your question is more of a product support one, so I'd suggest you ask it over at the Apple Support Forums. Thanks.