1 - just addressing one dimension of your first question: my mentor taught me to start with the minimum subscription tech stack necessary and let pain tell you when it's time to invest money in more technology---that's been good advice so far to limiting costs to only those items that bring a ROI through more deals and more efficiency. you can pretty much do everything for free when you start out this land investing journey---soon as you start making deals, the pain ratchets up, telling you where to upgrade next.
2 - i'd put my money on not taking action as the most common pitfall
3 - recommend do the wholesale deals once you have a chunk of properties under your belt. You need confidence on the process, due diligence, and pricing, as well as having your systems established, before you can confidently make deals with other investors. You could easily tie up lots of capital on marginal deals if you skip the training wheels phase. On the other hand, if acquisition is just too slow through your direct mail efforts, there is something to be said for dipping your toe in with wholesale deals just to get the buy/sell experience---caveat emptor is all.
4 - no i wouldn't---concur with Seth's comment---do some small deals yourself, follow and learn the processes, ask for help from other investors (feel free to ask me). you'll undoubtedly make some mistakes---if you are not, then you are making the biggest mistake of all, which is avoiding making yourself uncomfortable. Use realtors later on if you'd like once you have the experience to make an informed decision on ROI and efficiency and can properly screen for a good agent.