@The Mighty HeroRoll20 is what I use for my maps. It's free to use, but paying also gives additional features (most of which are more useful in live games). I also have a few dungeon modules that I could zip up and send to you, if that would be helpful. They are sized to Roll20's grid sizes.
I hope this isn't taken poorly. I see where Dust is coming from with the railroad comments. I was hoping we would have a chance to talk (both among ourselves and to our NPC ally) before arriving at the mansion. I think in most live games, the conversation would have normally been easier to achieve, bit a lot of us are waiting for responses (either from other PCs or the DM), and things can get overlooked. I certainly do not envy your personal situation, and my heart goes out to you. I hope once things settle back into a rhythm, you will have the time and energy to give us a bit more info in the posts.
One typical suggestion I would give: unless something is directly stated to us, we don't know it exists. The DM posts are typically used in PbP to set the scene. I suggest writing said post without considering any DMPC's perspective, and then tack on his reactions and actions on top of the DM post. It's certainly difficult to describe every aspect of what the PCs see, but on the other hand, we do have Perception rolls we could make and questions we could ask. I think most of us would request that we would not need to ask for important setting information that everyone would automatically see, such as what Dust mentioned about how tall the building is, how many obvious entrances, what info is on the map of the manor, etc.
On the other hand, asides from a goliath and his basketball team of pooches (Air Bud: D&D edition?), no one has even really stepped foot passed the gate (at least until Crow Eater's rolls). So we would have limited knowledge from this distance anyways... but I'm not really sure what the distance from the gate to the door is, or even if it's bright enough outside to see clearly.
The feeling of railroading doesn't fully come from a lack of description. Our characters were discussing a plan in the tavern: to get more info on our journey to the manor and get to know each other ever so slightly more. In the next post, we were at the manor with the chosen plan not enacted upon. Again, I'm not trying to be rude or point fingers, just hoping to give constructive criticism. Perhaps one way in the future that this could be avoided would be to have the NPC monologue at us along the journey, explaining more info as seems fit, and then giving us a chance to respond one way or another before we are at our destination. The reason that conversation along the road is helpful is because while our group is in public and considering illegal action, they are less likely to talk about themselves; and while we are at the front door of the supposed enemy, everyone is more guarded or looking for danger. But as I don't generally believe in retcons unless necessary, I feel like we can all move forward and hopefully not have similar issues in the future.