Is there PvP gear for characters under the level cap

It's actually sort of confusing. There is a lot of posts out there, including from official SWTOR sites that don't tell the whole story. Most of them suggest that there aren't inherit stats. Which is sort of true, but not totally:

From SWTOR Stats & Attributes:

Due to the extreme amount of gear customization in TOR, developers want you to be able to take any orange item (orange = fully moddable) and use it all the way to max level if you prefer. In order to achieve this, weapons and armor both have a dynamic stat on them which changes based on the level of the mods you have placed inside the item.

• Rating – Increases the damage done on a weapon. You’ll see this listed at the very top of a lightsaber or blaster’s tooltip. The stat itself does absolutely nothing except increase the damage done — think of it as the ‘item level’ stat you’re used to seeing in games like World of Warcraft.
• Armor – Armor, which you should be more familiar with, increases Energy and Kinetic resistances (more on that later), is the dynamic stat increased on pieces of equipped gear.

So, for an example, if you take an orange lightsaber with all level 1 mods in it, compared to the same lightsaber with all level 10 mods in it, the Rating stat will be much higher, and thus so will it’s damage. Same goes for Armor on those pieces with Armor on them.

(Which is a good summary from this really long SWTOR.com forum thread that did have an op post in it that clarified the situation to what we know now.)

The op explained that this dynamic stat is important so that modded items can drop from bosses on instance and still have some inherit value so that the first boss in an instance isn't farmed over and over for only the mod pieces.

The above SWTOR.com thread also discusses one important bug that is confusing a lot of people. If you do not equip the weapon/armor or relog after modifying it, the tooltip will not accurately reflect all the correct stats based on this dynamic stat modifier. Depending on what you change, when, and what is in it now, the numbers in the tooltip can be a lot higher or lower than they really are.

UPDATE:

Some additional clarification from the official devs:

Orange Armor gets it's armor value from the 'armoring' mod you slot in. If you exchange it for something better, the armor value increases along with the stats.

It's always the first mod in the list that determines the intrinsic properties of the orange items (e.g. armoring on armor, barrel on guns, etc.)

yes, DoTs become effects on the target, so when you die they remain.

Haven't you died in PvE after you kill a mob but the DoT kills you? same thing in PvP.