@Paul T. it really comes down to where you are in your journey as a business owner. I have been fortunate enough to work with some awesome REIs across the country who have outgrown "out-of-the-box" CRM offerings for a multitude of reasons... In these cases, building a custom Podio suite that is fully tailored to their business and processes is 100% the absolute best solution as it provides flexibility, leverage and a proprietary asset that no one else in their market has access too. With that said, if you're not at that stage, it can be very frustrating if you're trying to have some simple funtionality here and there; this might be a good use case for a "out-of-the-box solution".
With this said, I know how you feel. I started in Podio nearly 7 years ago and used it as no more than a glorified excel spreadsheet for nearly 3 years. I slowly picked up tips and tricks and added functionality to my workspaces and apps. I now have seen the flip side (huge automation stacks, calculations and automations) and know that competing with a fine-tuned custom built podio suite is hard to beat.
For your case, I would recommend sticking with it. I always challenge my clients to scrub their data BEFORE putting it into Podio. Excel has some very easy duplicate deletion features that can help you do this. In the even that your adding to existing Podio data, Podio does have a primary key/unique record solution when uploading data... but the trick is creating unique identifiers (first name is not sufficient as there are 100s of "Mary's" on a list, phone numbers can be difficult from multiple traces) so it's important to use Excel to create these unique identifiers. We could dive into this deep, but just to make a point... create a "Unique ID" field in excel that combines the last name plus first 3 numbers of the address (ex. Mary Smith at 123 Main St. would be "smith123" -- by doing this, you can use this column as your unique identifier to avoid adding duplicates.
Now, for the second portion of your question.... when it comes to outbound communication and if/then actions, Podio does not have many native features that make this easy... If you've seen my posts, you will know that the day that I was able to pair ActiveCampaign to Podio, for this very reason, was one of the best days of my life! Since then, i've had the opportunity to work with ActiveCampaign corporate to find awesome solutions for Real Estate Investors... if you'd like, I can get you an account for free, as well as an REI walk-through to help you with this exact function.
Hope this helps!