Most web designers or developers have their own web site which has hosting. You can simply create a subfolder on your hosting account and drop the web site into that... and access it via http://www.yourdomain.com/subfolder. If you don't have a hosting account, get one. They run as little as $40 a year.
Other options include using things such as MAMP, LAMP, ...
There are a couple of different options
Skala Preview - Works only on Mac, mobile app works for iOS or Android
A short description from their website
Skala Preview sends lossless, colour accurate image previews to any
iOS or Android device. Previews are pixel perfect. Colours are
identical to how the final app or website will look on the device.
I think you're misunderstanding how designing for mobile compares to designing for desktop. Luke Wroblewski described the difference best in his post "Organizing Mobile":
"[Simply] porting over what worked for you on the desktop to mobile often doesn’t make sense. Instead, you need to think about what mobile is uniquely good at and align it with the ...
Turns an iPad into a little mini Cintiq. It not only shows you the canvas, but allows you to work on the tablet and changes are reflected, real time, on the primary computer. (and vice versa)
Mac only though.
I think this amounts to the level of construction and visual complexity you want for any particular web build at any particular resolution of display.
It is entirely possible to use 1 image for every possible screen resolution. You can use 1 small image and let it look poor on more 4k/retina screens. Or you can use 1 large image and let it slow load times ...
Keeping it simple, and without any actual text....
...a black, right-pointing, arrow (intuitively meaning "next")...
...... and a grey check mark (intuitively meaning "done")...
Although.. I'd also maybe want to alter the text at the top and screen that back as well....
As for "other areas" outlined in the question.. I'd ...
960 grid system was an interesting option when the 1024x768 px monitors were the standard.
Sayed that it could work for a tablet with that resolution.
But I am afraid that that is an old aproach, so forget about it. Simply define some colums as you want them and let them re-escale.
Use either CSS Flexbox or CSS Grid.
A car's cockpit is a good orientation aid for this. Aim for high contrast. Black background and possibly white graphics/text. Black absorbs sunlight so it isn't reflected back to the user. Colored elements need to be a little bit larger than normal.
This will be very easy for you.
Photoshop CC, all cloud based software around $20 US a month
GIMP is free and very close to the above
Fast way to alter color of each icon:
Go to "layer style" then "color overlay"
Save again as PNG
This way, your icon will recolor and your background stays transparent.
If you have access to the Adobe Creative Cloud, you can view live previews of your website on any kind of mainstream mobile device using Edge Code and Edge Inspect. Changes happen as you edit in Edge Code, so you can get instant feedback on how different devices will handle changes to the HTML and CSS without having to continually push changes up to a server ...