How to determine which p-type GTO to choose in HF method?
Have a look in the Gaussian manual if something is unclear.

If you want to use an extern basis set in Gaussian you have to respect the gaussian input conventions for the basis set, which you can find here (gaussian.com/gen/). Since you are using the EMSL Basis Set Exchange the server gives you a file that satisfies these conventions. Like:

Type  NGauss  Sc
$α_1\quad d_{1μ}$
$α_2\quad d_{2μ}$
…
$α_N\quad d_{Nμ}$  

Type stands for the shell, then you have the number of primitives with NGauss and scaling factor Sc. Afterwards you put your exponents and coeffients of the primitive gaussian functions which then will be contracted to the respective contracted gaussian functions. You might notice that the scaling factor is set to unity for almost all basis sets—I checked some Dunning, Pople and Ahlrichs basis sets and always found it set to unity, which seems resonable. In the TURBOMOLE format the scaling factor is omitted totally, so it seems to be a Gaussian specific hack.

Now to your second question. You are specifing the shell, not a single function, a shell contains always all spherical harmonics belonging to the given quantum number or all cartesian gaussian functions. The spherical harmonics are the solution of the Schrödinger equation for an electron on a surface. You have generally $2l+1$ spherical harmonics where $l$ is the azimudal quantum number specified as 0/s, 1/p, 2/d, 3/f, 4/g, 5/h and so on. There exists also the possibilty to use cartesian gaussians with $(l+1)(l+2)/2$ degenerated functions.

Why am I telling you that? You always choose a whole shell with a azimudal quantum number, how many function belong to this shell depends on the quantum chemistry code you are using. ASAIK, Gaussian supports both.

In case of a p-shell it does not matter, both expressions evaluate to three p-functions (as expected). So you get three p-functions with one p-shell.

The basis set you have chosen would be evaluted as:

(9s4p1d) → [3s2p1d]

Having nine primitive s type gaussians (note that Dunning basis sets use a general contraction scheme), four primitive p type gaussians and one primitive d type gaussian which form a basis set out of three s shells, two p shells and one d shell with 14 contracted spherical harmonic gaussian functions or 15 contracted cartesian gaussian functions for carbon.