Research leads to Questions in Naming & Device

I sat down and did some research.So now I have questions, I want to get my last name in place and am trying to follow the guidelines to register. I am not ready to register yet, but it's a project I'm working on, so I'd love some input.

First: Given Name: Una
Proof of use:
Edmund Spenser's incomplete epic poem The Faerie Queene published in 1590
Una referenced page 218 [Woulfe] first edition, original print date 1923 republished 2007

Secondly: Sur Name: This I find very cool, but Tobin is an Irish Sur name common in the medieval area of Ireland especially in the Kilkenny area, which is an area of interest. There is documentable proof of Tobin as an Irish surname, site reference: www.surnamedb.com/surname/Tobin

I would like to use that surname, but thought Una Tobin might not be right. The Mac is for son of, O is grandson, Der is daughter of. I wasn't sure exactly how I should string the given to sur name and was hoping you could help me with how that name might work out.

I was also thinking of using a surname that would reference "from the swamps" or "of the swamps" but it's not quite as cool. How would one use something like the above to create their surname? Just a flat translation or do you have to find it in the history books to document it as usable?

Lastly, I am deliberating between two devices and I was wondering if you had any electronic versions of the heraldic symbols. Could you let me know if either of these styles would be acceptable:

Device A: Sable background. Silver Chevron. In the upper right and left above the chevron, each a silver oak leaf. In the triangle area below the chevron, a silver phoenix.

Device B: Sable background. Diagonal slash lower left to upper right. Parallel to the slash in the upper area are three oak leaves. Centered along the slash in the lower area is a single flower.

I was looking at the heraldic symbols and found oak leaves and flower... but there are way too many phoenix symbols and I wasn't sure what was correct.

I'm curious to know, of those two ideas, does it seem like I'm following the proper frame for a device? Are oak leaves, flowers or phoenixs reserved symbols that the general user is not allowed to use?

Does anyone have the heraldic symbol for the phoenix I could see?