It's really difficult to say how hard it will be. During Peak times, it's almost a given you won't be able to to it as Disney probably won' t have much "deposited" into the RCI system. Even during non-peak times, there are a LOT of people who look to trade into DVC and have alerts and notices set up to give them a heads up that DVC is available so they can grab it quickly.
It also usually doesn't work on a wyndham point to DVC point process. You would make a deposit of X type week of a certain room type from wyndham into the RCI system. You would then try and trade your deposited week for a week someone else deposited into RCI. Unfortunately, from what I've heard, Wyndham doesn't usually have a very strong trade power in the RCI system... and there are a lot of other gotcha's that come up when trying to do an RCI trade....especcially into DVC. (For instance, I think DVC charges a $75 "Transportation fee" to anybody trading into the resort)
That being said.... Since you own Wyndham, I'd honestly say it's not worth trying to get into DVC. With any timeshare, the real value comes from using it within the internal system. (This is the points version of the old "Own where you want to go" wisdom). Wyndham has an EXTREMELY nice resort that is actually closer than some of the DVC properties to the parks in the Bonnet Creek resort. If you check out the "We Loooove Bonnet Creek!" thread, you can see where a LOT of people love the resort and feel it is the same as being on property (as in the views and proximity.). The rooms also tend to be larger than DVC.
As for the Dining plan, While it may help save you some stress by allowing you to prepay for your meals, You can honestly come out ahead and have a more enjoyable/relaxing trip since you are staying offsite by not tied to Disney Dining. If you have a car, you will be able to run off property and enjoy some of the nice dining options outside the Disney gates.... Or you could even run to the Grocery Store and stock up on supplies so that you can cook or prepare meals within your resort room since it has a full kitchen.
Another thing to consider if you are planning multiple Disney trips would be an Annual Pass. If you can fit 2 vacations into the year the pass is valid, it's often cheaper than buying tickets for each vacation. If you are someone who enjoys TS meals, the Tables in Wonderland card is often a better deal than the Dining plan since it also includes discounts on Alcoholic Beverages and you are free to order what you want without having to stay within the confines of the
DDP. The free Parking also comes in handy since you are staying offsite.
Ultimately, you will discover that owning Timeshare and staying offsite will change some of the ways you are used to vacationing. The extra space and flexibility will open up a lot of options which if you were exclusively an onsite hotel room type of person just weren't available to you.
