Should I invest in a computer to do photo editing, or should I invest in more lenses? If I should go with the computer first should I go desktop or laptop? Any suggestions?
Depends, do you need lenses for what you want to do, you can always get your lenses you want,, they are places in some areas that you can rent work stations on site, prices vary but are affordable, so you can edit your stuff there, and some of these places use both windows systems and mac , so if you want you can test out both and see what you like best.
both windows and mac work great, it's all a matter of preference..
I would advise to stay away from laptops to do editing, they are not as good for display and laptops tend to cost more money, for what you would pay
for a laptop you could get a better desktop system.
I'm a windows guy always have always will, being that i use to work for Microsoft for years.
Years ago windows and DOS platform was buggy and had problems, but all that has been taken care of today's windows works great.
Now you don't have to go this way, but what i tend to advise people when they ask is, to get the best widows desktop system you can afford, try to go with SSD drives because they work faster.
What i use to edit my images and i shoot RAW because this is the best way to go more flexible and you can recover images better when you shoot raw.
I use Adobe Lightroom & Photoshop for my post-production work.
Adobe Lightroom & Photoshop are awesome, and you can get them cheap, you can lease both lightroom and photoshop as a package for only $9.99 a month, they have a few packages you can join up with,
the one i use to get both lightroom and photoshop is the photography package.
years ago you use to have to buy each one of them for a high price and when they came out with the newer version you had to upgrade spending money almost every year, this got quite expensive, with this deal you never own them but you lease them for only $9.99 a month and get all the updates and newer versions automatically, so you always have the newest version of both software.
you can even pay less by leasing them by the year, for a bit less then $9.99 a month, the only catch is you pay for the entire year up front.
but you end up paying less.
you can check out all the plans they have available to you. here
Adobe Creative Cloud
you can even check out some of there other software you might have interest as well and get deals on leasing.
now you can get another package that has most of there software in it, for $49.99 a month, and that is a deal .
I don't because i only use 3 of the adobe software, Lightroom photoshop and Premiere Pro, i pay $19.99 on top of the $9.99 for the photography package for the Premiere Pro..
Bur for right now for photography, Lightroom and photoshop is all your going to ever need for now until you start doing more advance stuff like video editing and rendering 3d in video's , for that i use Premiere Pro.
Now for a monitor,you want a good monitor because when you do your post editing you want the colors and settings to be accurate as possible.
i use a QHD monitor. benQ sw2700PT 27" .
and you also want to calibrate it each time you do your editing, i use the X-Rite Colormunki, cost like $400.00 but it will do all the work for you when you calibrate your monitor.
If you chose not to use that you might end up with incorrect settings and when you go to get your work printed they will look differently then what you expected and saw on your monitor..
Calibrating it will ensure everything is correct when you edit your pictures..
Even Highlights and contrast will be effected as well as color..
Now this is if you are trying to be serious about your images and want them to be as perfect as they can be, if your just taking pictures to share on Facebook then you don't really need to do any of that..
If you get serious and or start to do weddings or something then you definitely want to do that, because chances are your customers would be getting different looking images then you intended especially when it comes to having prints made..
Hope this helps..