Lance,
I also use a Garmin with the OS LR 1:50000 UK complete. I plan my hikes using Basecamp and the Landranger map which loads into Basecamp when the unit is plugged in. I always cross refer the planning in Basecamp to a paper Explorer map plus the OSM map which you can load into Basecamp ( available here
http://talkytoaster.info/ ) and finally for a complete overview of the plan Basecamp will link directly in to Google Earth.
For my hikes now it is the Garmin and LR map leading the way but with the paper Explorer map and compass always in the rucksack as a backup. Rarely ever do I need to cross refer to the paper map when out as I am quite meticulous in my original planning. It works extremely well and allows me to spend more time hiking and less time looking at maps and operating a compass. Of course you need those skills and should always practice them from time to time but the technology has most definitely freed me up whilst out there. So essentially the setup gives me confidence of where I am and where I am going, enough information for my own level of "situational awareness " and should the technology fail or I find I do need more then the paper map is available if need be.
Basecamp is without a doubt a work in progress piece of software. It does have a tricky learning curve but do persevere with it as it does work although often in a convoluted way. It has just been given a recent update that fixed quite a few things but introduced a few other bugs as well. There is a lot of help in the Garmin Forum here
https://forums.garmin.com/forum.php under Windows or Mac there is a Basecamp forum which is full of information tricks and tips, and some very knowledgeable people who will help.
As mentioned already the instruction manuals from Garmin are rubbish. I have learnt more about my sat nav from this site ( see Lyles excellent satnav set up list
http://micronavigation.com/the-resource-centre/ ) or watch his videos and you will gain a lot of knowledge about your sat nav you never knew existed! The set up is very important and makes a real difference. I don't know if you have Lyles book, but in there you will find a comprehensive sat nav guide which is a great source of reference.
To answer your other question planning a walk in Basecamp use tracks to do this. Once your track is planned you can create a route with waypoints if you wish by simply selecting "create route from track " option . Of course once you have walked the walk you will have an accurate track ( sat nav set up again ! ) to load back into Basecamp for accurate fine tuning and editing, after which you can now send back to the Garmin as your final polished track for future use. This workflow works rather well for me. Also in Basecamp latest version there is Garmin Adventures where you can download other peoples hikes / tracks complete with waypoints, descriptions and photo references. This gives you a good overview of how the planning works and if you are near any of these you can navigate them. I have uploaded two in the south east of England so wont be too hard to find
Time permitting I will upload some more.
Finally I recommend you copy the map files to a spare memory stick. This means you can plug the memory stick into any computer with Basecamp loaded and view the map if the unit is not with you or available. Can be very useful when travelling.
If you need a bit more help with Basecamp settings, or want to know what mine are give me a shout.
So this means you will have a fair bit of gin left over. I will PM you my address for delivery details