SThere are both advantages and disadvantages
Although technology of chemical explosive is very old and low-tech, it still remains very practical for asteroide mining. The reason is that chemical explosives provides very high density of mechanical work and force which cannot be so easily and efficiently achieved by other means (e.g. by use of solid mechanical tool, lasers, electron guns or railguns ). While chemical explosives provide much lower work density than nuclear explosives, those cannot be easily scaled down to proprotions practical for gentle and controlable mining. Chemcial explosives are usually applied in sophisticated manner by miniature robots which carefully maps gelogical structure of asteroide masive to find most suitable crack where application of explosive will be most efficient. The ammount of explosives used is much smaller thant is common in 20-century mines on earth, due to more advanced measuing techniques and atomatic analysis done by robots. It is desirable that the mechanical work exerted by explosives is just sufficent to split solid rock to pieces, but does not acclerate those pieces to hight velocity into space. Therefore consumption of explosives is actually very low per mass of mined raw material. The explosives can be produced fairly easily in situe even by low-tech chemistry. The only limitation may be ammount of nitrogen-rich substances (amonia ice, amonia salts and tritrates) or chlorates as its substituent. Nevertheless, chlorates and perchlorates can be certainly generated from cloride salts by electrolytic oxidation. These are actually more potent explosives, although not much used on earth (due to lower safety, and higher price and predominantly due to abundance of cheap nitirc acid). Also purely HCO explosives can be made e.g. in form of organic peroxydes and ozonides. These substances are generally oxygen-defficient therefore which limits theyr work potential and brisance. Therefore oxidizer in form of liquid oxygen or hydrogen peroxide is very desirable. Various mixures of fine hydrocarbons with oxygen will be perhaps most suitable explosive for mining application, due to its simple production from commodieits produced anyway in for rocket fuels and life support cycle.
In long term scope, it is certainly advantagenous to organize many smaller asteorieds into cluster (cities). The motivation (i) to improve connection and reduce transport cost and time for interdependnet economic processes and (ii) to scale up ammount of concentrate economical which increase efficiencey by economy of scale and allows to achieve some critical mass for more-sophisticated higher level industries. However, moving of asterieds represent considerable technical chalange. The phase-space of all posible orbits occupied by asteroides is fairly large (and 4 dimensional), so the average distance between reasonably sized asteorieds (100-10000m) is also large. Therefore there is considerable $\Delta$-v cost for any such manuever. Even in case when asteroides occupy almost the smae orbit, the orbital synchonization will be either costly (in $\Delta$-v) or will take long time (10-100 years). Considering large mass of moved objects, very cheap means for accleration of these object are required. The best per-impuls-cost is provided certainly by nuclear bombs which ablate surface material of asteroides. Nevertheless, this methods generated large instantenous accleration and shock in the surface, which many fragile ruble-pile asteroides cannot bare (they will spalate large fraction of surface mass). Also the methods is not particularily friently to already build infractructure of kolonized asteroieds. Threfore also more gentle methods are employed. Most effective is use nuclear thermal or solar thermal rocket with in-situe harvested volatiles used as propellant. When material of asteroide in depleted of volatiles chunks of asteoride material acclerated by electromagnetic mass-driver are used as propelant. Building such mass driver and sufficient supply of electrical energy is much more costly than simple thermal rocket (in per-impulse costs).